CBSE Questions for Class 11 Engineering Physics Laws Of Motion Quiz 1 - MCQExams.com

A uniform rod $$AB$$ is suspended from a point $$X$$, at a variable distance $$x$$ from $$A$$, as shown. To make the rod horizontal, a mass $$m$$ is suspended from its end $$A$$. A set of $$(m,x)$$ values is recorded. The appropriate variables that give a straight line, when plotted, are: 
868156_69c97df4ba824229a14c1d67b8824e0a.png
  • $$m,\cfrac { 1 }{ x } $$
  • $$m,\cfrac { 1 }{ { x }^{ 2 } } $$
  • $$m,x$$
  • $$m,{ x }^{ 2 }$$
A beaker of radius r is filled with water (refractive index $$\dfrac{4}{3}$$) up to a height H as shown in the figure on the left. The beaker is kept on a horizontal table rotating with angular speed $$\omega$$. This This makes the water surface curved so that the difference in the height of water level at the center and at the circumference of the beaker is $$h (h << H, h << r)$$, as shown in the figure on the right. Take this surface to be approximately spherical with a radius of curvature R. Which of the following is/are correct? (g is the acceleration due to gravity)
1950083_de2ad4e35027430e80de4ca82388e7f9.png
  • $$R = \dfrac{h^2 + r^2}{2h}$$
  • $$R = \dfrac{3r^2 }{2h}$$
  • Apparent depth of the bottom of the beaker is close to $$\dfrac{3H}{2} \left(1 + \dfrac{\omega^2 H}{2g} \right)^{-1}$$
  • Apparent depth of the bottom of the beaker is close to $$\dfrac{3H}{4} \left(1 + \dfrac{\omega^2 H}{4g} \right)^{-1}$$
What is the minimum velocity with which a body of mass $$m$$ must enter a vertical loop of radius $$R$$ so that it can complete the loop?
  • $$\sqrt{gR}$$
  • $$\sqrt{2gR}$$
  • $$\sqrt{3gR}$$
  • $$\sqrt{5gR}$$
  • 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
  • Both Assertion and Reason are incorrect
A ball is suspended by a thread of length L at the point O on a wall which is inclined to the vertical by $$\alpha$$. The thread with the ball is displaced by a small angle $$\beta$$ away from the vertical and also away from the wall. If the ball is released, the period of oscillation of the pendulum when $$\beta > \alpha$$ will be 
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[\pi+2sin^{-1}\frac{\alpha}{\beta}\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[\pi-2sin^{-1}\frac{\alpha}{\beta}\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[2sin^{-1}\frac{\alpha}{\beta}-\pi\right]$$
  • $$\displaystyle \sqrt{\frac{L}{g}}\left[2sin^{-1}\frac{\alpha}{\beta}+\pi\right]$$
An object placed on a ground is in stable equilibrium. If the objects is given a slight push, then initially the position of centre of gravity:
  • moves nearer to ground
  • rises higher above the ground
  • remains as such
  • may remain at same level
Cleaning of dust from carpet is due to _____.
  • Inertia of motion
  • Inertia of rest
  • Inertia of direction
  • Momentum
A ball of mass 'm' moves normal to a wall with a velocity 'u' and rebounds with the same speed. The change in momentum of the ball during the rebounding is
  • 2mu towards the wall
  • 2mu away from the wall
  • zero
  • mu away from the wall
When an athlete takes part in a long jump he runs for a while and then jumps. This is because:
  • inertia of motion helps him to take a longer jump.
  • running for a time makes him alert.
  • it helps him to focus on the point of jump.
  • he can apply more force for the jump after running.
Statement A: If the force varies with time then the net force is measured by the total change in momentum of the body.
Statement B: Change in momentum and impulsive force are numerically equal.
  • A & B are correct
  • A & B are wrong
  • A is correct and B is wrong
  • A is wrong and B is correct
Which of following Newton's laws reveals the underlying symmetry in the forces that occur in nature?
  • First law
  • Second law
  • Third law
  • Law of gravitation
When a moving body is suddenly stopped, then:
  • Frictional force increases.
  • Friction force remains same as it was while the car was moving.
  • Friction force reduces but has a non zero value.
  • Frictional force reduces to zero as it is a self adjusting force.
When a body is in equilibrium, which of the following must be true ?
  • There is no force acting on it.
  • The sum of all the forces acting on it must be zero.
  • The sum of all the forces acting on it is not equal to zero.
  • There are exactly two forces acting on the body.
Impulse is equal to
  • momentum
  • change in momentum
  • rate of change of momentum
  • rate of change of force
A stone tied to a string is rotated in a vertical circle. The minimum speed with which the stone has to be rotated in order to complete the circle :
  • decreases with increasing the mass of the stone
  • is independent of the mass of the stone
  • decreases with increasing the length of the string
  • is independent of the length of the string
Action and reaction
  • always act on two different bodies
  • are equal in magnitude
  • act in opposite directions
  • All the above
In which of the following cases the net force is not equal to zero?
  • A kite skillfully held stationary in the sky.
  • A ball falling freely from a height.
  • A helicopter hovering above the ground.
  • A cork floating on the surface of water.
The impulse of a body is equal to :
  • Rate of change of its momentum.
  • Change in its momentum.
  • The product of force applied on it and the time of application of the force.
  • Both (B) and (C)
Which of the following statements are correct regarding linear momentum of a body?
  • It is a measure of quantity of motion contained by the body.
  • Change in momentum is the measurement of impulse.
  • Impulse and acceleration act in same direction to the change in momentum.
  • Incase of uniform circular motion, the linear momentum is conserved.
Which of the following statements are true?
  • When the mass of a body is doubled then the momentum of a body is also doubled, provided the body maintains the same velocity.
  • We feel pain in the hand on hitting the wall, this is a consequence of Newton's third law of motion.
  • A table cloth can be pulled from a table without dislodging the dishes. This is due to inertia of rest.
  • Momentum is a vector quantity.
The average force necessary to stop a hammer with 25 N-s momentum in 0.05s expressed in N is :
  • 500
  • 125
  • 50
  • 250
....................... is a self adjusting force.
  • Magnetic Force
  • Electrostatic Force
  • Frictional Force
  • All 
Newton's first law of motion gives the concept of inertia.
  • True
  • False
If two balls each of mass 0.6 kg moving in opposite directions with speed of 4 m s$$^{-1}$$ collide and rebound with same speed, then the impulse imparted to each ball due to other is:
  • $$0.48 kg m s^{-1}$$
  • $$0.53 kg m s^{-1}$$
  • $$0.81 kg m s^{-1}$$
  • $$0.92 kg m s^{-1}$$
The time, in which a force of 2 N produces a change as momentum of 0.4 kg m s$$^{-1}$$ in the body is :
  • 0.2s
  • 0.02s
  • 0.5s
  • 0.05s
A hammer of mass 5 kg moving with a speed of 2 m s$$^{-1}$$ strikes the head of a nail driving it 20 cm into the wall. Find the impulse.
  • 10 N s
  • 20 N s
  • 30 N s
  • 40 N s
A ball tied to a string is swung in a vertical circle. Which of the following remains constant?
  • Tension in the string.
  • Speed of the ball.
  • Centripetal force.
  • Earth's pull on the ball.
Newton's third law:
  • defines the force qualitatively
  • defines the force quantitatively
  • explains the way the force acts on a body
  • gives the direction of force
The linear momentum of a ball of mass $$50  g$$ is $$0.5  kg  { m  s }^{ -1 }$$. Find its velocity.
  • $$0.01$$ $${ m s }^{ -1 }$$
  • $$1$$ $${ m s }^{ -1 }$$
  • $$5$$ $${ m s }^{ -1 }$$
  • $$10$$ $${ m s }^{ -1 }$$
'The action and reaction are equal in magnitude'. Is this statement true and which law is related with it ?
  • Yes, Newton's second law.
  • Yes, Newton's third law.
  • No, Newton's third law.
  • Yes, Newton's first law.
A metal ball does not rebound when struck on a wall, whereas a rubber ball of same mass when thrown with the same velocity on the wall rebounds. From this it is inferred that:
  • change in momentum is same in both.
  • change in momentum in rubber ball is more.
  • change in momentum in metal ball is more.
  • initial momentum of metal ball is more than that of rubber ball.
A body of mass $$5   kg$$ is moving with velocity $$2  { ms }^{ -1 }$$. Calculate its linear momentum. 
  • $$2.5$$ $$kg$$ $${ ms }^{ -1 }$$
  • $$10$$ $$kg$$ $${ ms }^{ -1 }$$
  • $$5$$ $$kg$$ $${ ms }^{ -1 }$$
  • $$20$$ $$kg$$ $${ ms }^{ -1 }$$
Momentum is most closely related to :
  • force
  • impulse
  • KE
  • power
A gun requiring the support of shoulder shows intensive recoil when fired with:
136694.png
  • the butt held tightly with the shoulder.
  • the butt held loosely against the shoulder.
  • butt held loosely or tightly against the shoulder.
  • a bullet of greater mass.
The SI unit of momentum is :
  • $$kg ms^{-1}$$
  • $$kg m s^{-2}$$
  • $$kg m s^{2}$$
  • $$kg m^{-1}s^{-1}$$
Frictional force always reduces:
  • Speed
  • Velocity
  • Acceleration
  • Time
The maximum force of friction when the body is just begining to move is known as the
  • Limiting friction
  • Rolling friction
  • Kinetic friction
  • (1) and (2) both
If the net force on an object is zero, then the object:
  • is in equilibrium
  • is not in equilibrium
  • may or may not be in equilibrium
  • always has zero mass
State whether given statement is True or False.
Force never exists in pairs.
  • True
  • False
Frictional force always opposes:
  • The state of rest
  • The state of motion
  • None of the above
  • Both the states
A force of $$10 N$$ acts on a body of mass $$20 kg$$ for $$10 s$$ .Change in its momentum is:
  • $$5 kg m/s$$
  • $$100 kg m/s$$
  • $$200 kg m/s$$
  • $$1000 kg m/s$$
You are on a frictionless horizontal plane. You can get off the plane :
  • by jumping
  • by throwing some pieces of stone
  • by rolling your body on the surface
  • by running on the plane
State whether given statement is True or False.
An object moving on a frictionless horizontal surface should move with constant velocity
  • True
  • False
The force of friction on a stationary body on a rough surface________  
  • will always be zero
  • might be zero
  • will be equal to the force of gravity
  • will be positive
The momentum of a 10 kg body moving at 36 km/h is:
  • 100 kg.m/s
  • 360 kg. m/s
  • 3.6 kg.m/s
  • 36000 kg .m /s
Momentum is a measure of 
  • Weight
  • Mass
  • Quantity of motion
  • Velocity
The combined effect of mass and velocity is taken into account by a physical quantity called :
  • torque
  • moment of force
  • momentum
  • moment of momentum
A metallic ball strikes a wall and falls down whereas a tennis ball having the same mass and velocity bounces back. The conclusion from this is that :
  • Both suffer equal change in momentum
  • The tennis ball suffers a greater change in momentum
  • Metallic ball suffers a greater change in momentum
  • The momentum of the tennis ball is less than that of the metallic ball
Impulse is a scalar quantity. State true or false.
  • True
  • False
Newton's first law of motion is also called Galileo's law of:
  • Conservation of momentum
  • Inertia
  • Friction
  • Conservation of mass
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