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question_answer1) What is the source of centripetal force that a planet requires to revolve around the sun? On what factors does that force depend?
question_answer2) An object is thrown vertically upwards and reaches a height of 10 m. Find (i) the velocity with which it was thrown up. (ii) time taken by it to reach the highest point. (g= 9.8 m/s2)
question_answer3) A car falls off a ledge and drops to the ground in 0.5. Find the speed on striking the ground. (i) its average speed during 0.5 s. (ii) height of ledge from the ground. (g = 10m/s2)
question_answer4) Two stones are taken and simultaneously thrown from a tower. One is thrown horizontally while other is dropped down. Which of them reaches the ground first and why?
question_answer5) Calculate the average density of earth in terms of g, G and R.
question_answer6) The weight of any person on moon is about 1/6th of that on earth. He can lift a mass of 15 kg on the earth. What will be the maximum weight which can be lifted by the same force applied by the person on the moon?
question_answer7) Given find the weight of a 5 kg object on (i) earth and (ii) moon.
question_answer8) A body is dropped from a height h. What is its height above the ground after 2 s of its fall? (g= 10 m/s2)
question_answer9) Find the gravitational force of attraction between a body of unit mass and moon, given mass of the moon radius of moon
question_answer10) A ball is dropped from a height half of the earth's radius. Find the value of g at this point.
question_answer11) How was Galileo able to conclude that the acceleration of an object falling freely towards the earth does not depend on the mass of the object?
question_answer12) Mention any four phenomena that the universal law of gravitation was able to explain.
question_answer13) Why does a body reach the ground quicker at poles than at the equator when dropped from the same height?
question_answer14) A stone is dropped from a cliff. What will be its speed when it has fallen 100 m?
question_answer15) How would the weight of an object change if it is initially weighed in Delhi and then taken to the (i) Poles (ii) Equator?
question_answer16) What will be the weight of the following objects on the earth when their weight on the moon is (i) 1800kg (ii) 400kg
question_answer17) Give two reasons for the variation of g at the equator and at the poles.
question_answer18) Estimate the gravitational force between two protons separated by a distance of 1 Å.
question_answer19) What is the acceleration due to gravity at a height from the surface of the earth (radius R) ?
question_answer20) A ball is thrown up with the velocity of 19.6 m/s. (i) How long will it take to reach the maximum height? (ii) How high will it go?
question_answer21) Define the term centre of gravity. Does it vary from centre of mass always. Give reason with an example.
question_answer22) What will be the weight felt by a man of mass (m) accelerating up with a lift by a m/s2 upwards?
question_answer23) On the earth, a stone is thrown from a height in a direction parallel to the earth's surface while another stone is simultaneously dropped from the same height. Which stone would reach the ground first and why?
question_answer24) Suppose gravity of earth suddenly becomes zero, then in which direction will the moon begin to move if no other celestial body affects it?
question_answer25) Identical packets are dropped from two aeroplanes, one above the equator and the other above the north pole, both at height h. Assuming all conditions are identical, will those packets take same time to reach the surface of earth. Justify your answer.
question_answer26) Find the weight of a 80 kg man on the surface of the moon? What should be his mass on the earth and on the moon? (g, = 9.8 m/s2 ,g^= 1.63 m/s2)
question_answer27) What is the distance covered by a freely falling body during the first three seconds of its motion? (Take g=10 m/s2 )
question_answer28) Give reasons (i) Moon does not have atmosphere. (ii) If you jump on the moon, you will rise much higher than if you jump on the earth.
question_answer29) Suppose that the radius of the earth becomes twice of its original radius without any change in its mass. Then, what will happen to your weight?
question_answer30) Give the characteristics of gravitational force.
question_answer31) In a hypothetical case, if the diameter of earth becomes half of its present value and mass becomes four times its present value, then how would the weight of any object on surface of the earth be affected?
question_answer32) A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when and where the two stones will meet. (g=10 m/s2 )
question_answer33) State Newton's law of gravitation, prove that it is a consequence of Newton's second law of motion.
question_answer34) Given, mass of earth =6xl024 kg, mass of moon =7 Ax 1022 kg. If distance between moon and earth is 3.84 xl05 km, find the gravitational force exerted by earth on moon.
question_answer35) What height above the surface of the earth, the value of g becomes 64% of its value cut the surface of the earth. Take the radius of the earth = 6400 km.
question_answer36) Write the standard equations in the form when an object is dropped from a height?
question_answer37) A ball is thrown upwards from the ground of a tower with a speed of 20 m/s. There is a window in the tower at the height of 15 m from the ground. How many times and when will the ball pass the windows? (Take g= 10 m/s2)
question_answer38) A ball is thrown with same velocity u m/s. Show that under the free fall, it will fall on the ground with same velocity.
question_answer39) Prove that if the earth attracts two bodies placed at the same distance from the centre of the earth with the same force, then their masses are equal.
question_answer40) How much would a 70 kg man weight in the moon? What would be his mass on the earth and on the moon? (Acceleration due to gravity on moon = 1.63 m/s2)
question_answer41) To find the height of a bridge over a river, when a stone is dropped freely in the river from the bridge. The stone takes 2 s to touch the water surface in the river. Calculate the height of the bridge from the water level (g = 9.8 m/s2).
question_answer42) Prove that if a body is thrown vertically upward, the time of ascent is equal to the time of descent.
question_answer43) On the earth, a stone is thrown from a height in a direction parallel to the earth's surface while another stone is simultaneously dropped from the same height. Which stone would reach the ground first and why?
question_answer44) Two bodies of masses 3 kg and 12 kg are placed at a distance 12 m. A third body of mass 0.5 kg is to be placed at such a point that the force acting on this body is zero. Find the position of that point.
question_answer45) A body weighs 25 kg on the surface of the earth. If the mass of the earth is 6 x 1024 kg, the radius of the earth is and the gravitational constant and the calculate (i) The mutual force of attraction between the body and the earth. (ii) The acceleration produced in the body. (iii) The acceleration produced in the earth.
question_answer46) (i) According to universal law of gravitational every object in this universe attracts every other object. Explain why then a table and a chair lying in the same room do not collide with each other. (ii) An object is thrown vertically upwards to a height of 12 m. Calculate its (a) velocity with which it was thrown upwards. (b) time taken by the object to reach a height of 12 m.
question_answer47) State the source of centripetal force that a planet requires to revolve round the sun. On what factors does the force depend? Suppose this force suddenly becomes zero, then in which direction will the planet begin to move, if no other celestial body affects it?
question_answer48) (i) Seema buys few grains of gold at the poles as per the instruction of one of her friends. She hand over the same when she meets her at the equator. Will the friend agree with the weight of gold bought? If not, why? (ii) If the moon attracts the earth, why does the earth not move towards the moon?
question_answer49) Manu is an archery trainer. While teaching his students, he asks them to keep the arrow a little above the target. Sonu is very curious to know the reason behind this and asks him. Manu explains very patiently to Sonu, on how the arrow travels when released. Read the above passage and answer the following questions (i) What explanation does Manu give to Sonu? (ii) What are the values of Sonu? (iii) What are the values of Manu?
question_answer50) Raju sees a kite string cut in the sky. He wants to catch it. So he stands just below the position to kite. To his dismay, the kite falls away much farther and is caught by someone else. He is very disappointed. He tells his grandfather that it should fall down straight just like a coin. His grandfather then explains him the reason behind this. He also buys him the new kite. Read the above passage and answer the following questions (i) Why does the kite not fall straight down? (ii) Give the list of values of Raju. (iii) Give the list of values of his grandfather.
question_answer51) Mohit throws a ball horizontally while Shobhit throws a ball vertically downwards from a tower. Both of them do so in an attempt to see who hits the stone on ground first. After that, they try to reason their findings. Read the above passage and answer the following questions (i) Which ball reaches the ground first? (ii) What are the values of Mohit and Shobhit?
question_answer52) Shikha buys a few grams of precious stones in Delhi. She takes them to equator and is surprised to see that their weight is reduced. She thinks that she has been cheated. She goes back to the seller and claims the exchange amount. The shopkeeper explains her how weight differs due to value of g. Satisfied, Shikha goes back. Read the above passage and answer the following questions (i) List few values of Shikha. (ii) What are the values of shopkeeper? (iii) How does g vary with distance?
question_answer53) Shikhaj was taught the concept of gravitation in class. He wondered why a table and chair not move towards each other. Confused, he goes to Prof. Raman who makes him sit and calculate the gravitational force between a table and chair of given masses. Shikhaj is now convinced about the small magnitude of these forces. Read the above passage and answer the following questions (i) What values of Prof. Raman must be noted? (ii) Which values of Shikhaj will you appreciate? (iii) How do you think practical situation helps in understanding something better?
question_answer54) Hemlata had a bad experience during the take off of the plane when she boarded it for the first time. Her friend assisted and helped her during the landing of plane. She told her to fasten the seat belt and involved her in gossip. Hemlata faced less problems while landing of the plane. Read the above passage and answer the following questions (i) Why do we tie our seat belts in moving cars or landing/ takeoff of the plane? (ii) What is free fall? (iii) What value of Hemlata's friend is seen in this act?
question_answer55) Two objects of masses and having the same size are dropped simultaneously from heights and respectively. Find out the ratio of time they would take in reaching the ground. Will this ratio remain the same if (i) one of the objects is hollow and the other one is solid and (ii) both of them are hollow, size remaining the same in each case. Give reason.
question_answer56) The radius of the earth at the poles is 6357 km and the radius at the equator is 6378 km. Calculate the percentage change in the weight of a body when it is taken from the equator to the poles.
question_answer57) How does the weight of an object vary with respect to mass and radius of the earth. In a hypothetical case, if the diameter of the earth becomes half of its present value and its mass becomes four times of its present value, then how would the weight of any object on the surface of the earth be affected?
question_answer58) Derive expression for force of attraction between two bodies and then define gravitational constant.
question_answer59) Define acceleration due to gravity. Derive an expression for acceleration due to gravity in terms of mass of earth (m) and universal gravitational constant.
question_answer60) How does the force of attraction between the two bodies depend upon their masses and distance between them? A student thought that two bricks tied together would fall faster than a single one under the action of gravity. Do you agree with his hypothesis or not? Comment.
question_answer61) From a cliff of 49 m high, a man drops a stone. One second later, he throws another stone. They both hit the ground at the same time. Find out the speed with which he threw the second stone.
question_answer62) Suppose the mass of the earth some how increases by 10% without any change in its size. What would happen to your weight? Suppose the radius of the earth becomes twice of its present radius without any change in its mass, what will happen to your weight?
question_answer63) Show that the weight of an object on the moon is l/6th of its weight on the earth.
question_answer64) (i) Will a sheet of paper fall slower than one that is crumpled into a ball in vacuum? Why? (ii) Show mathematically that acceleration experienced by an object is independent of its mass. (iii) Show that value of Given,
question_answer65) (i) At some moment, two giant planets Jupiter and Saturn of the solar system are in the same line as seen from the earth. Find the total gravitational force due to them on a person of mass 50 kg on the earth. Could the force due to the planets be important? Mass of the Jupiter = 2 x 1027 kg Mass of the Saturn = 6 x 1026 kg Distance of Jupiter from the earth Distance of Saturn from the earth Gravitational constant, Acceleration due to gravity on the earth (ii) A bag of sugar weighs W at a certain place on the equator. If this bag is taken to Antarctica, will it weigh the same or more or less. Give a reason for your answer.
question_answer66) State two factors on which the gravitational force between two objects depends.
question_answer67) What would happen if the centrifugal force between moon and earth vanish away?
question_answer68) The earth is acted upon by gravitation of sun even then it does not fall into the sun. Why?
question_answer69) How is acceleration due to gravity of a falling body related to its mass?
question_answer70) Which force bring tides in the ocean?
question_answer71) Identify the device used to measure weight of a body.
question_answer72) How does the weight of a body vary with its height.
question_answer73) Name the device used to measure mass of a body.
question_answer74) When a body is thrown upwards its velocity becomes zero at the highest point. What will be its acceleration at this point?
question_answer75) in vacuum, which of the two a feather and a coin reach the ground first on being dropped?
question_answer76) The astronauts in space feel weightless. Why?
question_answer77) What will be mass and weight of a unit mass at the centre of earth ?
question_answer78) Why should the bullet be fired a little above the line of target?
question_answer79) What exerts greater attractive force on the other earth on an apple or apple on the earth?
question_answer80) Name the place on the earth's surface where the weight of a body is maximum and minimum?
question_answer81) Does air resistance very with surface area of the body?
question_answer82) Two masses 4 kg and 2 kg are dropped from 5 m and 10 m from the ground respectively. Which will be accelerated more?
question_answer83) When a spring balance, holding a mass is let fall freely, what is the reading it will show?
question_answer84) What keeps the moon in uniform circular motion around the earth?
question_answer85) What is the final velocity, when a body is dropped from a height?
question_answer86) Which force causes things to fall towards the earth?
question_answer87) Anu buys 100 g of gold at the poles. What will be the weight of gold at equator?
question_answer88) Two objects attract each other with an attractive force F. If masses of both the objects are doubled, calculate the new force between them.
question_answer89) An object is put the one by one in three liquids having different densities. The object floats with and parts of their volumes outside the liquid surface in liquids of densities and respectively. Arrange and in increasing order.
question_answer90) Two particles are placed at some distance. If the mass of each of the two particle is doubled, keeping the distance between them unchanged, what will be the value of gravitational force between them?
question_answer91) An apple falls from a tree because of gravitational attraction between the earth and apple. If is the magnitude of force exerted by the earth on the apple and is the magnitude of force exerted by apple on earth, then find the relation between and .
question_answer92) Although gravitational force which acts on the bodies is proportional to their masses, then why do heavy bodies not fall faster than lighter bodies.
question_answer93) Two bodies of different masses are allowed to fall freely. How do their accelerations vary? Compare,
question_answer94) When do we use the term 'force of gravity' rather than' force of gravitation'?
question_answer95) At which place on the earth, the acceleration due to gravity is zero.
question_answer96) Where can the weight of a body be zero, apart from the centre of the earth?
question_answer97) If the earth attracts an apple, does the apple also attract the earth. If yes, why does the earth not move towards the apple?
question_answer98) Name the scientist who determined the value of universal gravitational constant.
question_answer99) If gravitational force acts between all objects, Why don't they move towards each other?
question_answer100) Distance between two objects is halved. How does the gravitational force between them change?
question_answer101) A stone dropped from a tree takes 2 s to reach the ground. Find its velocity on striking the ground.
question_answer102) Suppose gravity of earth suddenly becomes zero, then which direction will the moon begin to move if no other celestial body affects it?
question_answer103) Two objects of masses and are dropped in vacuum from a height above the surface of earth ( is greater than ). Which one will reach the ground first and why?
question_answer104) In Newton's universal law of gravitation, what does universal mean ?
question_answer105) How does the value of g vary with height above the ground?
question_answer106) What will happen to the gravitational force between two bodies if the masses of one body is doubled?
question_answer107) What do you mean by free fall? [NCERT]
question_answer108) Why is 'G' called the universal gravitational constant?
question_answer109) Who formulated the universal law of gravitation?
question_answer110) How is gravitation different from gravity?
question_answer111) What does a small value of G indicate?
question_answer112) At what place on the earth's surface is the weight of a body maximum?
question_answer113) At what place on the earth's surface is the weight of a body minimum?
question_answer114) If the mass of a body is 9.8 kg on the earth, what would be its mass on the moon?
question_answer115) Do fluids possess weight?
question_answer116) Why can one jump higher on the surface of the moon than on the earth?
question_answer117) Define the standard kilogram.
question_answer118) If the earth attracts two objects with equal force, can we say that their masses must be equal?
question_answer119) Is weight a force?
question_answer120) What keeps the moon in uniform circular motion around the earth?
question_answer121) When a body is dropped from a height, what is its initial velocity?
question_answer122) When a body is thrown vertically upwards, what is its final velocity?
question_answer123) Is the time taken by a body to rise to the highest point equal to the time taken to fall from the same height?
question_answer124) Is the acceleration due to gravity acting on a freely falling body directly proportional to the (a) mass of the body? (b) time of fall of the body?
question_answer125) Suppose gravity of earth suddenly becomes zero, then which direction will the moon begin to move if no other celestial body affects it? [NCERT Exemplar]
question_answer126) The earth is acted upon by gravitation of sun, even though it does not fall into the sun. Why? [NCERT Exemplar]
question_answer127) If the small and big stones are dropped from the roof of a house simultaneously, they will reach the ground at the same time. Why?
question_answer128) The earth attracts an apple. Does the apple also attract the earth? If it does, 'why does the earth not move towards the apple?
question_answer129) State the universal law of gravitation.
question_answer130) Write the formula to find the magnitude of the gravitational force between the earth and an object on the surface of the earth.
question_answer131) Mention any four phenomena that the universal law of gravitation was able to explain.
question_answer132) When does an object show weightlessness?
question_answer133) Why does a body reach the ground quicker at poles than at the equator when dropped from the same height?
question_answer134) What do you mean by acceleration due to gravity? [NCEAT]
question_answer135) Suppose that the radius of the earth becomes twice of its original radius without any change in its mass. Then what will happen to your weight?
question_answer136) How does the force of gravitation between two objects change when the distance between them is reduced to half? [NCERT]
question_answer137) Gravitational force acts on all objects in proportion to their masses. Why then, a heavy object does not fall faster than a light object? [NCERT]
question_answer138) Prove that if the earth attracts two bodies placed at same distance from the centre of the earth with the same force, then their masses are equal.
question_answer139) Give three differences between acceleration due to gravity (g) and universal gravitational constant (G).
question_answer140) Amit buys few grams of gold at the poles as per the instructions of one of his friends. He hands over the same when he meets him at the equator. Will the friend agree with the weight of gold bought? If not, why? [NCERT]
question_answer141) Why will a sheet of paper fall slower than one that is crumpled into a ball? [NCERT]
question_answer142) What is the source of centripetal force that a planet requires to revolve around the sun? On what factors does that force depend? [NCERT Exemplar]
question_answer143) On the earth, a stone is thrown from a height in a direction parallel to the earth's surface while another stone is simultaneously dropped from the same height. Which stone would reach the ground first and why? [NCERT Exemplar]
question_answer144) Calculate the average density of the earth in terms of g, G and R. [NCERT Exemplar]
question_answer145) The earth and the moon are attracted to each other by gravitational force. Does the earth attract the moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why? [NCERT]
question_answer146) If the moon attracts the earth, why does the earth not move towards the moon? [NCERT]
question_answer147) What is the importance of universal law of gravitation? [NCERT]
question_answer148) What is the acceleration of free fall? [NCERT]
question_answer149) Prove that if a body is thrown vertically upward, the time of ascent is equal to the time of descent. [NCERT Exemplar]
question_answer150) Derive expression for force of attraction between two bodies and then define gravitational constant.
question_answer151) What are the differences between the mass of an object and its weight? [NCERT]
question_answer152) Why is the weight of an object on the moon th its weight on the earth? [NCERT]
question_answer153) Define acceleration due to gravity. Derive an expression for acceleration due to gravity in terms of mass of the earth (M) and universal gravitational constant (G).
question_answer154) Show that the weight of an object on the moon is of its weight on the earth.
question_answer155) What happens to the force between two objects, if (i) the mass of one object is doubled? the distance between the objects is doubled and tripled? (ii) the masses of both objects are doubled?
question_answer156) How does the weight of an object vary with respect to mass and radius of the earth? In a hypothetical case, if the diameter of the earth becomes half of its present value and its mass becomes four times of its present value, then how would the weight of any object on the surface of the earth be affected? [NCERT Exemplar]
question_answer157) Why does formation of tides takes place in sea or ocean?
question_answer158) Why does a body orbiting in space possess zero weight with respect to a spaceship?
question_answer159) Identical packets are dropped from two aeroplanes?one above the equator and other above the North Pole, both at height h. Assuming all conditions to be identical, will those packets take same time to reach the surface of earth? Justify your answer.
question_answer160) How does the force of attraction between the two bodies depend upon their masses and distance between them? A student thought that two bricks tied together would fall faster than a single one under the action of gravity. Do you agree with his hypothesis or not? Comment. [NCERT Exemplar]
question_answer161) Velocity-time graph for the ball's motion is shown in figure. Observe the graph and answer the following questions. Assume that g = 10 m/s2 and that there is no air resistance. (a) In which direction is the ball moving at point C? (b) At which point is the ball stationary? (c) At which point is the ball at its maximum height? (d) What is the ball's acceleration at point C? (e) What is the ball's acceleration at point A? (f) What is the ball's acceleration at point B? (g) At which point does the ball have the same speed as when it was thrown?
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