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:
$$1 \,N$$ that force which produces acceleration of $$1 \,m \,s^{-2}$$ in a body of mass $$1 \,g.$$
  • True
  • False
The momentum of a body of given mass is proportional to its:
  • speed
  • volume
  • density
  • shape
Two small spheres of masses $${M}_{1}$$ and $${M}_{2}$$ are suspended by weightless insulating threads of lengths $${L}_{1}$$ and $${L}_{2}$$, the spheres carry charges $${Q}_{1}$$ and $${Q}_{2}$$ respectively. The spheres are suspended such that they are in level with another and the threads are inclined to the vertical at angles of $${\theta}_{1}$$ and $${\theta}_{2}$$ as shown, which one of the following conditions is essential, if $${ \theta  }_{ 1 }={ \theta  }_{ 2 }:$$
823708_d0c367fa6aac4b42924a373221a67bcf.png
  • $${ M }_{ 1 }\neq { M }_{ 2 }$$ but $${ Q }_{ 1 }={ Q }_{ 2 }$$
  • $${ M }_{ 1 }= { M }_{ 2 }$$
  • $${ Q }_{ 1 }={ Q }_{ 2 }$$
  • $${ L }_{ 1 }={ L }_{ 2 }$$
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

  • $$7875 \ kg \,m/s$$
  • $$3.5 \ N$$
  • $$5.0 \ m/s$$
  • $$7.875\ kg \ m/s$$
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
  • $$F_{net} = 0$$; No
  • $$F_{net} \neq 0$$; No
  • $$F_{net} = 0$$; Yes
  • $$F_{net} \neq 0$$; Yes
A rocket with a lift-off mass $$3.5\times {10}^{4}\ kg$$ is blasted upwards with an initial acceleration of $$10m{s}^{-2}$$. Then the initial thrust of the blast is:
  • $$3.5\times {10}^{5}N$$
  • $$7.0\times {10}^{5}N$$
  • $$14.0\times {10}^{5}N$$
  • $$1.75\times {10}^{5}N$$
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
  • $$(F_{net}) = 0$$ ; Balanced Forces
  • $$(F_{net}) \neq 0$$; Balanced Forces
  • $$(F_{net}) = 0$$; Unbalanced Forces
  • $$(F_{net}) \neq 0$$; 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:
  • $$\sqrt {m}$$
  • $$m^{o}$$
  • $$\dfrac {1}{\sqrt {m}}$$
  • $$m$$
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 $$20{ms}^{-2}$$ 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? ($$g = 10 \mathrm { m }  \mathrm { s } ^ { -2 }$$) 
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 $$800{ ms }^{ -1 }.$$ The final velocity acquired by the person and the average force exerted on the person are
  • $$-0.8{ ms }^{ -1 },16N$$
  • $$-0.8{ ms }^{ -1 },8N$$
  • $$-1.6{ ms }^{ -1 },16N$$
  • $$-1.6{ ms }^{ -1 },8N$$
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 ..........
  • $$0.1\ ft/sec$$
  • $$0.2\ ft/sec$$
  • $$0.4\ ft/sec$$
  • $$0.8\ ft/sec$$
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Class 9 Physics Quiz Questions and Answers