Laws of Motion Test

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Laws of Motion Test - 21

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Question 1
1 / -0

The combined effect of mass and velocity is taken into account by a physical quantity called :

A
torque

B
moment of force

C
momentum

D
moment of momentum

Solution

Mass ad velocity both are considered to be quantities which defines motion.
The combination of both is called quantity of motion.
It is momentum.
$$ P = mv$$
Question 2
1 / -0

Frictional force always reduces:

A
Speed

B
Velocity

C
Acceleration

D
Time

Solution

As a body is set in motion on surface (not frictionless) a frictional force starts acting on the body in the direction opposite to the motion of the body. Friction always opposes the state of motion.
Question 3
1 / -0

Frictional force always opposes:

A
The state of rest

B
The state of motion

C
None of the above

D
Both the states

Solution

As a body is set in motion on surface (not frictionless) a frictional force starts acting on the body in the direction opposite to the motion of the body.
Question 4
1 / -0

A force of $$10 N$$ acts on a body of mass $$20 kg$$ for $$10 s$$ .Change in its momentum is:

A
$$5 kg m/s$$

B
$$100 kg m/s$$

C
$$200 kg m/s$$

D
$$1000 kg m/s$$

Solution

$$\Delta P = F\Delta t = 10 \times 10 = 100 kg m/s$$
Where,
$$\Delta$$ P = Change in momentum,
F = Applied force
$$\Delta$$ t = time for which force has been applied on the body
Question 5
1 / -0

You are on a frictionless horizontal plane. You can get off the plane :

A
by jumping

B
by throwing some pieces of stone

C
by rolling your body on the surface

D
by running on the plane

Solution

One has to apply a force on a stone to throw it forward and, in return, the stone will apply equal and opposite reaction force helping one to get off the surface.
Question 6
1 / -0

Momentum is defined as :

A
weight

B
mass

C
mass$$\times$$velocity

D
velocity

Solution

Momentum is product of mass and velocity.
also known as "quantity of motion"'.
Question 7
1 / -0

The force of friction on a stationary body on a rough surface________

A
will always be zero

B
might be zero

C
will be equal to the force of gravity

D
will be positive

Solution

Friction is a force that always opposes motion.
For a stationary body, it may be zero but it is also possible that it has some magnitude. As in the case of pushing a heavy object, the frictional force can be equal to the force applied but still, the body is stationary.
It can only be equal to the gravitational force on the object, only when the coefficient of friction of the rough surface is equal to one.
And frictional force cannot be positive because it always opposes the motion.
So, the correct option is (B).
Question 8
1 / -0

In which of the following cases the net force is not zero?

A
A kite skillfully held stationary in the sky

B
A ball freely falling from a height

C
An aeroplane rising upwards at an angle of $$45^{\circ}$$ with the horizontal with a constant speed

D
A cork floating on the surface of water

Solution

If a ball freely falling from a height the net force applied on the ball is not zero as gravity is acting on it.
Question 9
1 / -0

What is the momentum of an object of mass m, moving with a velocity v?

A
$$(mv)^2$$

B
$$mv^2$$

C
$$\dfrac {1}{2} mv^2$$

D
$$mv$$

Solution

Correct Option is D.
Explanation for the correct answer:
$$\bullet$$Momentum is a vector quantity, defined as the product of mass and velocity of a body.It is denoted by $$p$$. Its direction is same as the velocity of the body.
$$\bullet$$Thus if a body of mass $$m$$ is moving with a velocity $$v$$, then momentum of the body is given as, $$p = mv$$

Thus, Option D is correct.
Question 10
1 / -0

Momentum is a measure of

A
Weight

B
Mass

C
Quantity of motion

D
Velocity

Solution

Momentum is mass* velocity.
For motion two questions are important, " How much is moving? " and "How fast is it moving?'
For change in state, inertia is necessary. Inertia is mass for translational motion.
So, Quantity of motion is momentum.

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Re-Attempt Weekly Quiz Competition

Laws of Motion Test - 21

Result

Laws of Motion Test - 21

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SHARING IS CARING

Question 1

torque

moment of force

momentum

moment of momentum

Solution

Question 2

Speed

Velocity

Acceleration

Time

Solution

Question 3

The state of rest

The state of motion

None of the above

Both the states

Solution

Question 4

$$5 kg m/s$$

$$100 kg m/s$$

$$200 kg m/s$$

$$1000 kg m/s$$

Solution

Question 5

by jumping

by throwing some pieces of stone

by rolling your body on the surface

by running on the plane

Solution

Question 6

weight

mass

mass$$\times$$velocity

velocity

Solution

Question 7

will always be zero

might be zero

will be equal to the force of gravity

will be positive

Solution

Question 8

A kite skillfully held stationary in the sky

A ball freely falling from a height

An aeroplane rising upwards at an angle of $$45^{\circ}$$ with the horizontal with a constant speed

A cork floating on the surface of water

Solution

Question 9

$$(mv)^2$$

$$mv^2$$

$$\dfrac {1}{2} mv^2$$

$$mv$$

Solution

Question 10

Weight

Mass

Quantity of motion

Velocity

Solution

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