Tag: physics

Questions Related to physics

If two bodies of different masses move with the same momentum, then heavier body will have greater velocity.

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. True

  2. False

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Correct Option: B
Explanation:

momentum is P = mv

so, $ p _1 = m _1 v _1 $ and $ p _2 = m _2 v _2 $
$ p _1 = p _2 $
so, $ m _1 v _1 =m _2 v _2 $
so, if $  m _1 > m _2, $ then $ v _1< v _2 $
So, given statement is false.

A car and a lorry are moving with same momentum, if same braking force is applied, then :

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. Car comes to rest in shorter distance.

  2. Lorry comes to rest in shorter distance.

  3. Both travels same distance before coming to rest.

  4. None

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Correct Option: B
Explanation:

A car and a lorry are moving with same momentum, if same breaking force is applied, then lorry comes to rest in shorter distance as it has greater mass so moves with less velocity.

To reduce the momentum of a given body to half its original value then the velocity must be __________.

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. reduced to half

  2. reduced to one-third

  3. doubled

  4. remain same

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Correct Option: A
Explanation:

P = mv

so, $ P _1 / P _2 = v _1 / v _2 $
So, if $ P _2 = 1/ 2 \space P _1$, 
then $v _2 = 1/2\space  v _1$
So option A is correct

The linear momentum of a body at rest is zero.

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

P= mv

if v = 0, then P = 0
So, given statement is correct.

A force acts on a body of mass 3 kg such that its velocity changes from 4 m s$^{-1}$ to 10 m s$^{-1}$. The change in momentum of the body is :

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. 42 kg m s$^{-1}$

  2. 2 kg m s$^{-1}$

  3. 18 kg m s$^{-1}$

  4. 11 kg m s$^{-1}$

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Correct Option: C
Explanation:

$\Delta p = m(v-u) = 3 (10-4)$
$=18 kg  m  s^{-1}$

Which of the following statements are true?

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. When the mass of a body is doubled then the momentum of a body is also doubled, provided the body maintains the same velocity.

  2. We feel pain in the hand on hitting the wall, this is a consequence of Newton's third law of motion.

  3. A table cloth can be pulled from a table without dislodging the dishes. This is due to inertia of rest.

  4. Momentum is a vector quantity.

Show answer
Correct Option: A,B,C,D
Explanation:

Option A is correct .

as P = mv,
So $ P \space \alpha \space m $ if v is constant.


Option B is correct.
The pain in hand is due to reaction from the wall. It will be same in magnitude as that of applied force according to Newton's third law, for every action, there is an equal and opposite reaction.


Option C is correct.
When table cloth is pulled very fast, due to inertia dishes does not change its state. 

Option 4 is correct.
P = mv
as v (velocity) is vector, momentum is also vector.

Which of the following statements are correct regarding linear momentum of a body?

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. It is a measure of quantity of motion contained by the body.

  2. Change in momentum is the measurement of impulse.

  3. Impulse and acceleration act in same direction to the change in momentum.

  4. Incase of uniform circular motion, the linear momentum is conserved.

Show answer
Correct Option: A,B
Explanation:

Momentum, P = Mv

So, it gives quantity of motion. Option A is correct.
By Newton's second law,
Ft = mv-mu, So option B is correct.
The direction of impulse can be opposite to that of change in momentum. Option C is wrong.
The Uniform circular motion is accelerated motion. So, momentum is not conserved.
Option D is wrong.
Hence, Options A and B are correct.

A force of 100 N acts on a body of mass 2 kg for 10 s. The change in momentum of the body is:

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. 200 N-s

  2. 250 N-s

  3. 500 N-s

  4. 1000 N-s

Show answer
Correct Option: D
Explanation:

$\displaystyle F = \frac{m(v-u)}{t}$


$ \displaystyle 100 = \frac{2 (v-u)}{10}$

$\Rightarrow (v-u) = 500 m  s^{-1}$

Change in momentum $=m (v-u)$

$= 2 \times (500)$

$= 1000 \ N - s$

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 :

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. 0.2s

  2. 0.02s

  3. 0.5s

  4. 0.05s

Show answer
Correct Option: A
Explanation:

$F=\displaystyle \frac{\Delta P}{t}$
$2 = \displaystyle \frac{0.4}{t} $ (or) $t = 0.2 s$

Coefficient of restitution is related to which of the follwing parameters?

physics force and newton's laws of motion momentum (p) introduction to momentum linear momentum

  1. Linear momentum

  2. Angular momentum

  3. Kinetic energy

  4. Moment of inertia

Show answer
Correct Option: C
Explanation:

The coefficient of the restriction is related to the kinetic energy.

The correct option is C.