CBSE Questions for Class 9 Physics Force And Laws Of Motion Quiz 14 - MCQExams.com

Which of the following statements is not true regarding the Newton's third law of motion?
  • To every action there is always an equal and opposite reaction.
  • Action and reaction act on the same body.
  • There is no cause-effect relation action and reaction.
  • Action and reaction forces are simultaneous forces.

984460_d072b0e008234d2987fa39d5c9a7f1b6.png
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect and Reason is correct
Complete the statement of the first law of motion. "A body at rest stays at ____ and a body in motion stays in ____ unless an ____ is applied" 
  • Motion; Rest; External Force
  • Rest; Motion; External Force
  • Rest; Motion; Internal Force
  • None of these
A force of 2 N is applied on a particle for 2 sec, the change in momentum will be -
  • 2 Ns
  • 4 Ns
  • 6 Ns
  • 9 Ns
Write true or false for the following statements:
1N that force which produces acceleration of 1ms2 in a body of mass 1g.
  • True
  • False
The momentum of a body of given mass is proportional to its:
  • speed
  • volume
  • density
  • shape
Two small spheres of masses M1 and M2 are suspended by weightless insulating threads of lengths L1 and L2, the spheres carry charges Q1 and Q2 respectively. The spheres are suspended such that they are in level with another and the threads are inclined to the vertical at angles of θ1 and θ2 as shown, which one of the following conditions is essential, if θ1=θ2:
823708_d0c367fa6aac4b42924a373221a67bcf.png
  • M1M2 but Q1=Q2
  • M1=M2
  • Q1=Q2
  • L1=L2
A free-floating astronaut A pushes another free-floating astronaut B in space. The mass of A is greater than that of B. The force exerted by the astronaut A on the astronaut B will be.
  • Greater than the force exerted by B on A
  • Equal to the force exerted by B on A
  • Equal to zero
  • Less than the force exerted by B on A
Which of the following is not the characteristics of matter?
  • The matter has a mass
  • Matter does not have inertia
  • Matter is affected by gravity
  • Matter cannot be destroyed

The momentum of a 225 g ball moving at 35 m/s is

  • 7875 kgm/s
  • 3.5 N
  • 5.0 m/s
  • 7.875 kg m/s
A ball is moving in the direction as shown. What will be the direction of momentum?
1005902_3809ea0c2d6e4c58aae24c47c1a45763.png
  • W
  • N
  • S
  • E
A fly strikes the windshield of a moving truck as shown. What can you say about the forces: the force on the fly and the force on the truck.

1006045_454275ab1c67461ab29caed5b064b0de.png
  • Force on the fly > Force on the truck
  • Force on the fly < Force on the truck
  • Force on the fly = Force on the truck
  • None of these
Club the cases shown under balanced or unbalanced forces (all arrows represent same magnitude of force)
1005880_ea867292d8b7454f83d92d6fa3e71ebd.png
  • Balanced forces- A,B and Unbalanced forces- C,D
  • Balanced forces- C,D and Unbalanced forces- A,B
  • Balanced forces- A,C and Unbalanced forces- B,D
  • Balanced forces- B,D andUnbalanced forces- A,C
Find net force on the object shown in the figure. Will the object move?
1005883_eb01bde866074daf9583291470cc91ed.png
  • Fnet=0; No
  • Fnet0; No
  • Fnet=0; Yes
  • Fnet0; Yes
A rocket with a lift-off mass 3.5×104 kg is blasted upwards with an initial acceleration of 10ms2. Then the initial thrust of the blast is:
  • 3.5×105N
  • 7.0×105N
  • 14.0×105N
  • 1.75×105N
A gun weighing 10 kg fires a bullet of 30 g with a velocity 330 m/s With what velocity does the gun recoil?
  • 2 m/s
  • 1 m/s
  • 0 m/s
  • 3 m/s
Find net force on the object shown in the figure and answer if the forces are balanced or unbalanced
1005887_a909635537ca4ed2ab78b0146b285fb1.png
  • (Fnet)=0 ; Balanced Forces
  • (Fnet)0; Balanced Forces
  • (Fnet)=0; Unbalanced Forces
  • (Fnet)0; Unbalanced Forces
The velocity acquired by a mass m in travelling a certain distance d starting from rest under the action of a constant force is directly proportional to:
  • m
  • mo
  • 1m
  • m
If the tension in the cable supporting an elevator is equal to the weight of the elevator, the elevator may be
  • Going up with increasing speed
  • Going down with increasing speed
  • Going up with uniform speed
  • Going down with uniform speed
Due to the application of a force on a body of mass 100 kg that is initially at rest, the body moves with an acceleration of 20ms2 in the direction of the force. Find the magnitude of the force.
  • 1000N
  • 2000N
  • 3000N
  • 4000N
5 kg block rests on horizontal surface. Which of the following option is correct? (g=10ms2
1194848_a5f8365d55c0480986796f6df779fd1a.png
  • The normal force on the block equals its weight because of Newton's second law
  • The normal force on the block is equal to the weight not because of Newton's third law
  • The normal force on the block equals its weight because of Newton's third law
  • The normal force on the block is 50 N.
Which of the following objects experience balanced forces? 
  • A ball dropping vertically
  • A car accelerating uniformly from rest
  • A trolley moving at a constant velocity down an inclined plane
  • A plane flying in a circle with constant speed
According to Newton's third law action is always equal and opposite to the reaction, a horse can pull a cart because it applies a ______.
  • Force on cart
  • Force on ground
  • Both A and B
  • None of these
A force of 15N acts separately on two bodies of masses 3kg and 5kg. The ratio of the acceleration produced in the two cases will be
  • 5:3
  • 3:5
  • 8:15
  • 15:8
Fill in the blanks.
At least _____________ objects must be present to experience a gravitational force. 
  • 1
  • 2
  • 3
  • 4
When a body is stationary 
  • there is no force acting on it
  • the forces acting on it are not in contact with it
  • the combination of forces acting on it balance each other
  • None of the above
When two bodies A and B interact with each other, A exerts a force of 10N on B towards east. What is the force exerted by B on A?
  • A exerts 10N force on B towards West
  • B exerts 20N force on A towards East
  • B exerts 10N force on A towards West
  • A exerts 20N force on B towards East
A person holding a rifle (mass of person and rifle together is 100 kg) stands on a smooth surface and fires 10 shots horizontal, in 2 s. Each bullet has a mass of 10 g with a muzzle velocity of 800ms1. The final velocity acquired by the person and the average force exerted on the person are
  • 0.8ms1,16N
  • 0.8ms1,8N
  • 1.6ms1,16N
  • 1.6ms1,8N
In the graph below is given the variation of force with time. Find out the net change in momentum of the object.
1300911_dca51fda52b34af7b33045fe6bf73d2c.png
  • 24 kg m/s
  • 10 kg m/s
  • 6 kg m/s
  • 3 kg m/s
From a stationary tank of mass 125000 pound, a small shell of mass 25 pound is fired with a muzzle velocity of 1000 ft/sec. The tank recoils with a velocity of ..........
  • 0.1 ft/sec
  • 0.2 ft/sec
  • 0.4 ft/sec
  • 0.8 ft/sec
0:0:2


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