Tag: linear momentum

Questions Related to linear momentum

The unit of linear momentum is:

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

  1. $N$ $s$

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

  3. $N$ ${ s }^{ -1 }$

  4. $k{ g }^{ 2 }$ $m$ ${ s }^{ -1 }$

Show answer
Correct Option: A
Explanation:

Linear momentum, $p=mv$
Unit of mass $=kg$
Unit of velocity $=m/s$
Hence, Unit of linear momentum $=kg m/s = kg m/s^2\times s = Ns$

A body of mass $5   kg$ is moving with velocity $2  { ms }^{ -1 }$. Calculate its linear momentum. 

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

  1. $2.5$ $kg$ ${ ms }^{ -1 }$

  2. $10$ $kg$ ${ ms }^{ -1 }$

  3. $5$ $kg$ ${ ms }^{ -1 }$

  4. $20$ $kg$ ${ ms }^{ -1 }$

Show answer
Correct Option: B
Explanation:

We know that $ p= mv$


where $p =$ linear momentum

$m=5kg$ mass, $v =2 m/s$ velocity

$ p = 5 \times 2 = 10 kg ms^{-1}$

A body P has mass 2 m and velocity 5 v. Another body Q has mass 8 m and velocity 1.25 v. Find out the ratio of momentum of P and Q.

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

  1. 2:1

  2. 1:1

  3. 1:2

  4. 3:2

Show answer
Correct Option: B
Explanation:

The momentum is given as $M= mv$

Where, $m= $ mass of object, 
              $v= $ velocity of object
Momentum of first object $= 2m\times 5v = 10mv$
Momentum of second object $= 8m\times 1.25v=10mv$, taking the ratio of the magnitude of momentum of Ist and IInd objects $ |p _1|:|p _2|= 1:1$
Hence, correct answer is B.

If the acceleration of an object is zero:

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

  1. it must be at rest

  2. it may or may not be at rest

  3. it must be moving

  4. it must be falling freely under gravity

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Correct Option: B
Explanation:

From newton's  2nd law of motion, the zero acceleration implies no external force, however, the body may have uniform velocity.

Hence the body may or may not be at rest.

State whether given statement is True or False.
It's possible to have motion in the absence of a force

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: A
Explanation:

From newton's  IInd law of motion, the zero acceleration implies no external force, however, the body may have uniform velocity.hence the statement is true, thus correct answer is A.

Momentum of a body is defined to be the product of its mass and:

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

  1. speed

  2. velocity

  3. acceleration

  4. none of these

Show answer
Correct Option: B
Explanation:

The momentum is given by mass times it's velocity, and it is a vector quantity with direction same as velocity. The question states momentum is mass times it's speed, which is incorrect since it gives a scalar value. Hence the statement is false and correct answer is B.

If a car and a truck are moving with same momentum, the velocity of car is ........... the velocity of truck.

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

  1. Greater than

  2. Lesser than

  3. Equal to

  4. might be lesser than

Show answer
Correct Option: A
Explanation:

We know, p$=$mv and the mass of car is less than truck.
However momentum are same, that shows  velocity of car is greater than the velocity of truck.

State whether the given statement is true or false :

A horse continues to apply a force in order to move a cart with a constant speed.

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:

Horse walking or running on the ground is a case of static friction. The horse moves forward but with each step it stops and then has to move again. Thus, it has to apply a constant force to keep moving.

If the ground were frictionless after the push, the horse and the cart would keep moving at the same velocity and would not be able to change the direction.

A ball rolling along a floor doesn't continue rolling indefinitely. This is because of:

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

  1. Friction

  2. Mass of the body

  3. earth's gravity

  4. force of attraction

Show answer
Correct Option: A
Explanation:

Force of Friction
It is the force of friction which is acting upon the ball and reducing its speed and finally making it zero.

State whether given statement is True or False.
Linear momentum is always in the direction of velocity

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:

Linear momentum is always in the direction of Velocity.
Linear momentum is a vector quantity defined as the product of an object's mass, m, and its velocity, v. Linear momentum is denoted by the letter p and is called momentum for short: Note that a body's momentum is always in the same direction as its velocity vector. .