Tag: physics

Questions Related to physics

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

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

  1. $(mv)^2$

  2. $mv^2$

  3. $1/2\ mv^2$

  4. $mv$

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Correct Option: D
Explanation:

Momentum of an object is defined as the product of its mass and the velocity with which the object is moving.

Let velocity of the object be  $v$ and its mass be  $m$
$\therefore \text{Momentum},\ P = mv$

A bullet of mass 40 g moving with a speed of $90 ms^{-1}$ enters a heavy wooden block and is stopped after a distance of 60 cm. The average resistance force exerted by the block on the bullet is

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

  1. 180 N

  2. 220 N

  3. 270 N

  4. 320 N

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Correct Option: C

Momentum is a measure of 

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

  1. Weight

  2. Mass

  3. Quantity of motion

  4. Velocity

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Correct Option: C
Explanation:

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.

A long-jumper runs before jumping to 

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

  1. Cover greater distance

  2. Maintain momentum conservation

  3. Gain energy by running

  4. Gain momentum

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Correct Option: D
Explanation:

While running a long distance, jumper tries to gain more velocity that increases his momentum. When he jumps, due this momentum, his body covers longer distance.

So, Option D is correct.

Force is directly proportional to

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

  1. Rate of change in distance

  2. Rate of change in velocity

  3. Momentum

  4. Rate of change in momentum

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Correct Option: D
Explanation:

Second law of motion yields $F = \Delta p/\Delta t$

Which has a greater momentum, an elephant at rest or an ant in motion?

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

  1. Elephant

  2. Ant

  3. Neither has momentum

  4. Same

Show answer
Correct Option: B
Explanation:

Momentum combines both mass and velocity. Ant has a greater momentum because of it is moving. Momentum of the elephant would be zero because it is at rest.

$SI$ units of momentum is _____ 

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

  1. $kg\, m/s^2$

  2. $kg \,m/s$

  3. $g \,km/hr$

  4. $kg\, km/hr$

Show answer
Correct Option: B
Explanation:

$SI$ unit of momentum $= (SI\, \text{unit of}\, m).(SI\,\text{ unit of}\, v) = kg \,m/s$

The SI unit of linear momentum is $kg \ m/s^{-1}$.

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:

Momentum = mv

Unit: kg * m/ s
So, given statement is true.

If the same force is applied on two bodies of different masses for the same time, then the change produced in the momentum of the two bodies is also same .

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:

According to Newton's second law,

F = ma = m (v - u)/ t
Ft = mv - mu = Change in momentum
Now, for two bodies, if Ft is same, change in momentum is also same.
So, given statement is true.

Momentum is a measure of quantity of motion.

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:

For motion there are two factors, How much is moving? and how fast is moving?

According to that force changes.
So mass and velocity both are important. Hence momentum(P = mv) is quantity of motion.