9th Class Science Force and laws of motion Question Bank

done MCQs - Force and Laws of Motion Total Questions - 42

• question_answer1)
  The resultant force acting on a body is zero, then
  A)
  body is in unequilibrium done clear
  B)
  body is in equilibrium done clear
  C)
  body moves with constant acceleration done clear
  D)
  body moves with retardation done clear
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• question_answer2)
  A force cannot change the speed of a moving object.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say           done clear
  D)
  Partially true/false done clear
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• question_answer3)
  If an unbalanced force is applied on the moving object there will be a change in its............ or in the............ of its motion.
  A)
  shape, speed                              done clear
  B)
  speed, direction done clear
  C)
  shape, direction                          done clear
  D)
  size, direction done clear
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• question_answer4)
  When a rubber balloon held between the hands is pressed, its shape changes. This happens because
  A)
  balanced forces act on the balloon done clear
  B)
  unbalanced forces act on the balloon done clear
  C)
  frictional forces act on the balloon done clear
  D)
  gravitational forces act on the balloon done clear
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• question_answer5)
  The inertia of an object tends to cause the object              (NCERT Exemplar)
  A)
  to increase its speed done clear
  B)
  to decrease its speed done clear
  C)
  to resist any change in its state of motion done clear
  D)
  to decelerate due to friction done clear
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• question_answer6)
  The inertia of a moving object depends on
  A)
  momentum of the object done clear
  B)
  speed of the object done clear
  C)
  mass of the object done clear
  D)
  shape of the object done clear
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• question_answer7)
  Dirty blanket is beaten by stick to remove dust particles. Which law holds good for this?
  A)
  Law of conservation of momentum done clear
  B)
  Law of inertia done clear
  C)
  Law of impulse done clear
  D)
  Law of conservation of energy done clear
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• question_answer8)
  A heavy objects will have more inertia than lighter one.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer9)
  Father has mass 60 kg and the mass of his son is 30 kg. The ratio of the inertia of the father to his child is
  A)
  1:1                                            done clear
  B)
  1:2 done clear
  C)
  2:1                 done clear
  D)
  1:3 done clear
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• question_answer10)
  An object of mass 2 kg is sliding with a constant velocity of \[4m{{s}^{-1}}\] on a frictionless horizontal table. The force required to keep the object moving with the same velocity is               (NCERT Exemplar)
  A)
  32N                                          done clear
  B)
  0N done clear
  C)
  2N                                            done clear
  D)
  8N done clear
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• question_answer11)
  A water tanker filled upto \[\frac{2}{3}\] of its height is moving with a uniform speed. On sudden application of the brake, the water in the tank would be            (NCERT Exemplar)
  A)
  move backward   done clear
  B)
  move forward done clear
  C)
  be unaffected      done clear
  D)
  rise upwards done clear
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• question_answer12)
  What is the SI unit of momentum?
  A)
  kg-ms            done clear
  B)
  ms/kg done clear
  C)
  \[Kg -m{{s}^{-1}}\]           done clear
  D)
  kg/ms done clear
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• question_answer13)
  The quantity of motion in a body is also known as ............ .
  A)
  Momentum                                done clear
  B)
  Velocity done clear
  C)
  Speed             done clear
  D)
  Acceleration done clear
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• question_answer14)
  An object of mass 4 kg moves with a velocity of 4 m/s, then its momentum will be
  A)
  16 m/s             done clear
  B)
  4 m/s done clear
  C)
  16 kg-m/s          done clear
  D)
  4 kg-m/s done clear
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• question_answer15)
  A faster moving body has greater momentum than a slower one irrespective of their masses.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer16)
  What will be the percentage change in momentum of a body when both its mass and velocity are doubled?
  A)
  400               done clear
  B)
  75 done clear
  C)
  500               done clear
  D)
  300 done clear
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• question_answer17)
  1 dyne is equal to
  A)
  \[{{10}^{5}}\] N                 done clear
  B)
  \[{{10}^{7}}\]N done clear
  C)
  \[{{10}^{-5}}\] N                done clear
  D)
  \[{{10}^{-7}}\]N done clear
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• question_answer18)
  One Newton is defined as the force which gives a mass of 1 kg and acceleration of............ .
  A)
  1km/h             done clear
  B)
  \[1m/{{s}^{2}}\] done clear
  C)
  \[1Km/{{h}^{2}}\]            done clear
  D)
  \[1m/{{s}^{2}}\] done clear
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• question_answer19)
  Two forces are acting on a body in different directions, then acceleration produced in the body is due to
  A)
  resultant of both forces done clear
  B)
  sum of both forces done clear
  C)
  difference of both forces done clear
  D)
  None of the above done clear
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• question_answer20)
  What is the numerical formula for force?
  A)
  F=ma                                       done clear
  B)
  \[F=\frac{m}{a}\] done clear
  C)
  \[\operatorname{F}=m{{a}^{2}}\]       done clear
  D)
  \[F={{a}^{2}}m\] done clear
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• question_answer21)
  A goalkeeper in a game of football pulls his hands backwards after holding the ball shot at the goal. This enables the goalkeeper to     (NCERT Exemplar)
  A)
  exert larger force on the ball done clear
  B)
  reduce the time for which force is exerted by the ball on hands done clear
  C)
  increase the rate of change of momentum done clear
  D)
  decrease the rate of change of momentum done clear
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• question_answer22)
  A student is able to move a block of mass 2 kg with minimum force of 1N. The force of friction between the object and the surface will be
  A)
  2 N                                           done clear
  B)
  0.9 N done clear
  C)
  1 N                                           done clear
  D)
  0 N done clear
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• question_answer23)
  A force acts on a body of mass 5 kg and changes its velocity from 8 m/s to 12 m/s in 4 s, then magnitude of force is
  A)
  8 N                                           done clear
  B)
  4 N done clear
  C)
  5 N                                           done clear
  D)
  6 N done clear
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• question_answer24)
  A truck moving with a speed of 54 km/h. Truck driver applied brakes suddenly and brings the truck to rest in 5 s, then the average retarding force on truck, if mass of the truck and driver is 400 kg, will be
  A)
  200 N           done clear
  B)
  600 N done clear
  C)
  800 N                                        done clear
  D)
  500 N done clear
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• question_answer25)

  Two forces \[{{\operatorname{F}}_{1}}\] and \[{{\operatorname{F}}_{2}}\] are acting on a body as shown in the figure, then acceleration in the body is

   
  A)
  \[23m/{{s}^{2}}\]            done clear
  B)
  \[3m/{{s}^{2}}\] done clear
  C)
  \[2m/{{s}^{2}}\]             done clear
  D)
  \[22m/{{s}^{2}}\] done clear
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• question_answer26)
  Match Column I with Column II and choose appropriate option from the codes given below.

  	Column I		Column II
  (A)	Change in momentum	1.	kg
  (B)	Momentum	2.	N
  (C)	Force	3.	\[\operatorname{Kg}-m{{s}^{-1}}\]
  (D)	Mass	4.	N-s

  Codes
  A)
  A-3,  B-4,  C-1,  D-2 done clear
  B)
  A-4,  B-1,  C-2,  D-3 done clear
  C)
  A-4,  B-3,  C-2,  D-1 done clear
  D)
  A-1,  B-2,  C-3,  D-4 done clear
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• question_answer27)
  When a moving body comes to rest, then its initial velocity is taken as zero.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer28)
  A bus of mass 500 kg is moving with a velocity of 5 m/s and is acted upon by a forward force of 500 N due to engine and retarding force of 200 N due to friction. Velocity of bus after 20 s will be
  A)
  15 m/s            done clear
  B)
  17 m/s done clear
  C)
  19 m/s            done clear
  D)
  21 m/s done clear
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• question_answer29)
  A bullet of 20 g strikes a sand bag at a speed of 200 m/s and gets embedded after travelling 2 cm, then the resistive force exerted by sand on the bullet is
  A)
  \[2\times {{10}^{3}}\operatorname{N}\]          done clear
  B)
  \[2\times {{10}^{4}}\operatorname{N}\] done clear
  C)
  \[2\times {{10}^{6}}\operatorname{N}\]                     done clear
  D)
  \[2\times {{10}^{5}}\operatorname{N}\] done clear
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• question_answer30)
  When a person jumps down from a tower into a stretched trapaulin, then he receives
  A)
  greater injury       done clear
  B)
  less injury done clear
  C)
  no injury            done clear
  D)
  None of these done clear
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• question_answer31)
  According to the third law of motion, action and reaction                 (NCERT Exemplar)
  A)
  always act on the same body done clear
  B)
  always act on different bodies in opposite directions done clear
  C)
  have same magnitude and direction done clear
  D)
  act on either body at normal to each other done clear
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• question_answer32)
  It is possible to walk if and only if third law of motion holds true.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer33)

  Consider two spring balances hooked as shown in the figure below. We pull them in opposite directions. If the reading shown by A is 1.5 N, then reading shown by B will be

  A)
  1.5 N                                        done clear
  B)
  2.5 N done clear
  C)
  3.0 N                   done clear
  D)
  zero done clear
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• question_answer34)
  Water sprinkler used for grass lawn begins to rotate as soon as the water is supplied. Identify the principle on which it works.
  A)
  Newton's first law of motion done clear
  B)
  Newton's second law of motion done clear
  C)
  Newton's third law of motion done clear
  D)
  Newton's universal law of gravitation done clear
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• question_answer35)
  Shock absorbers are provided in the vehicles to smooth out shock impulses which obeys Newton's first law.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer36)
  Match the column I with column II and choose the appropriate option from codes given below.

  	Column I		Column II
  (A)	Recoil of gun	1.	Newton’s 2nd law of motion
  (B)	Inertia	2.	\[1{{0}^{5}}g-cm{{s}^{-1}}\]
  (C)	Momentum	3.	Newton's 3rd law of motion
  (D)	\[1kg-m{{s}^{-1}}\]	4.	Newton's 1st law of motion

  Codes
  A)
  A-3,  B-4,  C-1,  D-2 done clear
  B)
  A-4,  B-1,  C-2,  D-3 done clear
  C)
  A-1,  B-2,  C-3,  D-4 done clear
  D)
  A-2,  B-4,  C-1,  D-3 done clear
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• question_answer37)
  Rocket works on the principle of conservation of       (NCERT Exemplar)
  A)
  mass                                         done clear
  B)
  energy done clear
  C)
  momentum                                done clear
  D)
  velocity done clear
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• question_answer38)
  The linear momentum of a system remains constant if no ............ force acts on it.
  A)
  internal                                      done clear
  B)
  external done clear
  C)
  Both [a] and [b]                          done clear
  D)
  None of these done clear
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• question_answer39)
  A body at rest explodes into two equal parts. Then, they move with
  A)
  different speeds in different directions done clear
  B)
  different speeds in same direction done clear
  C)
  same speed in same direction done clear
  D)
  same speed in opposite directions done clear
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• question_answer40)
  The law in which the sum of product of masses and velocities of two moving bodies before and after their collision remains constant is known as law of conservation of mass.
  A)
  True                                          done clear
  B)
  False done clear
  C)
  Can't say                                   done clear
  D)
  Partially true/false done clear
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• question_answer41)
  Two objects of masses 1 kg and 2 kg are moving with velocities 2 m/s and 4 m/s, respectively. They collide and after collision the first object moves at a velocity 3 m/s, then velocity of second object is
  A)
  3.5 m/s done clear
  B)
  4.5 m/s done clear
  C)
  2.5 m/s done clear
  D)
  0 m/s done clear
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• question_answer42)
  A bullet of mass 30 g is fired horizontally with a velocity of 120 m/s from a pistol of mass 2 kg, the recoil velocity of the pistol is
  A)
  1.6 m/s                done clear
  B)
  2.8 m/s done clear
  C)
  2.4 m/s                done clear
  D)
  1.8 m/s done clear
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