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question_answer1) A cricket ball of mass 70 g moving with a velocity of 0.5 m/s is stopped by a player in 0.5 s. What is the force exerted by the player to stop it?
question_answer2) A force of 30 N produces an acceleration of m/s2 in a body of mass m. Find the mass of the body. Also find the acceleration if force is doubled in magnitude along the same direction.
question_answer3) Two children stand on wheel-carts facing each other. One student throws a heavy mass towards the other who catches it. What will be the direction of motion of both the children? Give reason for your answer.
question_answer4) Find the acceleration and force acting on a body of mass 4 kg using the following v-t graph.
question_answer5) A car is moving horizontally on a surface along a straight line at constant speed. Is any force acting on it? If not, why is the fuel required to run it?
question_answer6) A bullet of mass 20 g is fired from a pistol of mass 2 kg with a horizontal velocity of 150 m/s. Calculate the recoil velocity of the pistol.
question_answer7) Name the forces acting on a book placed on a table. Why does the book not move on its own if forces are acting on it?
question_answer8) For how much time should a force of 200 N acts on an object having mass 5 kg so as to increase its velocity from 50 m/s to 100 m/s?
question_answer9) Give two applications of inertia in daily life.
question_answer10) Make a pile of similar carom coins on a table. Then remove the lower coin without touching the other coins. With your fingers, you may give a sharp horizontal hit at the botton of the pile using sticker. What will happen if the hit is strong enough? What will happen to the remaining coins once the lower coin is removed?
question_answer11) Why can a small mass such as a bullet kill a person when fired from a gun?
question_answer12) Why does the pillion rider fall forward when brakes are applied?
question_answer13) A bullet fired against a glass window pane makes a hole in it and the glass pane is not cracked. But on the other hand, when a stone strikes the same glass pane, it gets smashed. Why is it so?
question_answer14) When small boy is trying to push a heavy stone, mention various forces acting on the stone.
question_answer15) The velocity-time graph of a ball of mass 30 g moving along a straight line on a long table is given in the figure alongside. How much force does the table exert on the ball to bring it to rest?
question_answer16) Why does a boat tend to leave the shore, when passengers are alighting from it?
question_answer17) There are three solids made up of aluminium, steel and wood, of the same shape and same volume. Which of them , would have highest inertia?
question_answer18) Describe our walking in terms of Newton's third law of motion.
question_answer19) Give few examples of Newton's third law of motion.
question_answer20) Two friends on roller-skates are standing 5 m apart facing each other. One of them throws a ball of 2 kg towards the other, who catches it? How will this activity affect the position of the two? Explain your answer.
question_answer21) Two balls of the same size but of different materials, rubber and iron, are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so, in which direction? Will they move with the same speed? Give reasons for your answer.
question_answer22) Two identical bullets are fired one by one by a light rifle and another by a heavy rifle with the same force, which rifle will hurt the shoulder more and why?
question_answer23) A horse continues to apply a force in order to move the cart with a constant speed. Explain why?
question_answer24) Suppose a ball of mass m is thrown vertically upward with an initial speed v, its speed decreases continuously till it becomes zero. Thereafter, the ball begins to fall downward and attain the speed v again before striking the ground. It implies that the magnitude of initial and final momentums of the ball are same. Yet, it is not an example of conservation of momentum. Explain why?
question_answer25) Take a test tube of good quality glass material and put a amount of water in it. Place a stop cork at the mouth of it. Now suspend the test tube horizontally by two strings or wires as shown in the figure. Heat the test tube with a burner until water vaporises and the cork blows out. Write any two of your observations.
question_answer26) Take a big rubber balloon and inflate it fully. Tie its neck using a thread. Also using adhesive tape, fix a straw on the surface of this balloon. Pass a thread through the straw and hold one end of the thread in your hand or fix it on the wall. Ask your friend to hold the other end of the thread or fix it on a wall at some distance. This arrangement is shown in the figure. Now remove the thread tied on the neck of balloon. Let the air escape from the mouth of the balloon. Observe the direction in which the straw moves. Give reason.
question_answer27) Take a test tube and pour a small amount of water in it. Seal its mouth with the help of a cork. Heat the test tube on a burner flame till all water turns into steam. What happens to the cork? Why does it happen? What might happen in case, cork was too tightly closed?
question_answer28) Two hockey players of opposite teams, while trying to hit a hockey ball on the ground, collide and immediately get entangled. One has a mass of 60 kg and was moving with a velocity of 5 m/s. The other has a mass of 55 kg and was moving with a velocity of 6 m/s, towards the first player. In which direction and with what velocity will they move after they become entangled? Assume that the frictional force acting between the feet of two players and ground is negligible.
question_answer29) Describe an activity to demonstrate Newton's third law of motion.
question_answer30) Give reasons for the following. Horse continues to apply force in order to move a cart with constant speed. Water sprinkler used for grass lawns begins to rotate as soon as water is supplied. Water drops are removed from wet clothes by giving tight jerk to the cloth.
question_answer31) Force of 10 N applied to a mass produces an acceleration of 5 and when applied to mass , produces an acceleration of 15 in the mass. How much acceleration will the same force produce if the two masses are tied together?
question_answer32) An iron sphere of mass 1 kg is dropped from a height of 10 m. If the acceleration of sphere is 9.8 , calculate the momentum transferred to the ground by the ball.
question_answer33) A bullet of mass 4 g when fired with a velocity of 50 ms -1, can enter a wall up to a depth of 10 cm. How much will be the average resistances offered by the wall?
question_answer34) A cracker of mass 100 g explodes into two pieces of equal mass. Show that these two pieces of the cracker fly in opposite direction.
question_answer35) The velocity-time graph of a ball moving on the surface of floor is shown in figure. Calculate the force acting on the ball if mass of the ball is 100 g.
question_answer36) A body of mass 300 g kept at rest breaks into two parts due to internal forces. One part of mass 200 g is found to move at a speed of 12 m/s towards the east. What will be the velocity of the other part?
question_answer37) A bullet of mass 0.02 kg is fired from a gun weighing 7.5 kg. If the initial velocity of the bullet is 200 m/s, calculate the speed with which the gun recoils.
question_answer38) A rifle of mass 3 kg fires a bullet of mass 0.03 kg. The bullet leaves the barrel of the rifle at a velocity of 100 m/s. If the bullet takes 0.003 s to move through its barrel, calculate the force experienced by the rifle due to its recoil.
question_answer39) Look at the diagram below and answer the following questions. When a force is applied through the free end of the spring balance A, the reading on the spring balance A is 15 g wt. What will be the measure of the reading shown by spring balance B? Write reasons for your answer. Name the force which balance A exerts on balance B and the force of balance B on balance A.
question_answer40) The motion of a body of mass 5 kg is shown in the v-t graph. Find from graph. it acceleration. the force acting on the body the change in momentum of body in 2 seconds after start.
question_answer41) Glass wares are wrapped in straw during their transportation. Justify giving reason.
question_answer42) The force of friction between the surface of a floor and the surface of a box in contact with the floor in 200 N. We wish to move the box on the floor with constant velocity. How much force has to be applied on the box?
question_answer43) Two friends on roller skates are standing 5 m apart facing each other. One of them throws a ball of 2 kg towards the other, who catches it. How will this effect the position of the two? Explain.
question_answer44) A boy pulls a table along the floor of a room. Name the forces acting on the table. Which of these forces perform positive work? Which of these forces perform negative work?
question_answer45) Give reasons and mention the law related to these statements. It is easier to push an empty box than to push the box full of books. It is difficult for a fireman to hold a hose which ejects large amount of water with high velocity.
question_answer46) A cracker of mass 100 g explodes into two pieces of equal mass. Show that these two pieces of the cracker fly in opposite direction.
question_answer47) Two friends were playing 'catch the ball' in a park. A was able to catch the ball comfortably without hurting himself, while 'B' was hurt every time he caught a ball. Finally B asked A how he could catch the ball with ease. A explained the phenomena to B. B thanked him. Why was A not hurt while catching the ball? Compare and contrast the values of A and B.
question_answer48) In order to find out force exerted by his car, Manoj plotted a velocity-time graph for his journey along a straight highway. He wondered if he did not accelerate after 1 min, where was the fuel spent by engine going. His wife then told him how his car was overcoming friction due to road. What are the values of Manoj? With what values is his wife equipped with? How will they find their total displacement?
question_answer49) William was having a gun-shoot session in a training camp. As soon as he shot a bullet, he fell backwards. Sanat started making fun of him. William stood up and explained the cause of this effect and told him not to laugh without understanding the scientific cause behind it. What explanation did William give to Sanat? Compare and contrast the values of William and Sanat. If you were in place of Sanat, how would you react to such a situation?
question_answer50) Two friends of class IX were sitting in a restaurant and try to push a pillar with all their might. The first one explains the situation that the pillar did not move because of its inertia while the second one says that it is because action and reaction forces cancel each other's effect. Which of the two friends give correct justification? Compare the values of both the boys. If Newton's third law holds good, why don't action and reaction forces cancel each other when we walk?
question_answer51) Mahi is fond of trying stunts. She jumps on a stationary cart while playing. Since cart wheels are frictionless, the cart begins to move forward and stops after covering some distance. Mahi probes to find out reasons for such observation and gives a correct interpretation too. What values of Mahi will you appreciate? What qualities of Mahi according to you, need to be modified? What were Mahi's interpretations?
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