Physics · Science General

Collisions, Momentum and Kinetic Energy

385 Questions

Collisions, momentum, and kinetic energy questions analyze the principles of elastic and inelastic impacts. They require calculating mass, velocity, and conserved energy during physical interactions. These foundational physics topics are essential for most government engineering and general science examinations.

Elastic collisionsInelastic collisionsMomentum calculationKinetic energy principlesVelocity after impact

Collisions, Momentum and Kinetic Energy Questions

Multiple choice physics force and newton's laws of motion concept of inertia galileo's law and inertia mass and inertia

P and Q are two objects with masses 5 kg and 30 kg respectively. Then

  1. P has more inertia than Q

  2. Q has move inertia than P

  3. P and Q have the same inertia

  4. neither P nor Q has any inertia
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Inertia has direct dependence on $mass$ of the body. More the mass of the body, more will be its inertia.

Since Q has more mass, thus Q has more inertia than P.

Multiple choice physics force and newton's laws of motion concept of inertia galileo's law and inertia mass and inertia

Two balls of the same size but of different materials, rubber and iron are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so, in which direction? Will they move with the same speed? 

  1. Iron ball is faster than rubber ball

  2. Rubber ball is faster than iron ball

  3. Both move at the same speed

  4. None of them move
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

(a) Inertia is the name for the tendency of an object in motion to remain in motion, or an object at rest to remain at rest, unless acted upon by a force. This concept was quantified in Newton's First Law of Motion. For example when a car is abruptly accelerated, drivers and passengers may feel as though their bodies are moving backward. In reality, inertia is making the body want to stay in place as the car moves forward.

(b) Yes, both the balls will start rolling due to inertia of motion. The train stops due to brakes. But the balls continue to move in the direction of the train. But the balls will not roll with the same speed. Iron ball will move slower than the rubber ball because it is heavier in weight.

Multiple choice physics behaviour of perfect gas and kinetic theory of gases mean free path law of equipartition of energy and mean free path behavior of perfect gas and kinetic theory

A molecule of gas in a container hits one wall (1) normally and rebounds back. It suffers no collision and hits the opposite wall (2) which is at an angle of $30^o$ with wall 1.
Assuming the collisions to be elastic and the small collision time to be the same for both the walls, the magnitude of average force by wall 2. $(F _2)$ provided the molecule during collision satisfy

  1. $F _1 > F _2$
  2. $F _1 < F _2$
  3. $F _1=F _2$, both non-zero
  4. $F _1=F _2=0$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Initial momentum, $P _1=mvcos 30$
and final momentum, $P _2 = mvcos30$
change in momentum
$\Delta P = -2mv cos30$
$\Delta P =-\sqrt 3 mv$
Force on wall-1
$F _1=\frac {2mv}{\Delta t}$
Force on wall-2
$F _2=\frac {\sqrt 3mv}{\Delta t}$, so $F _1 > F _2$

Multiple choice physics dynamics - explaining motion system of unit summary of si units system of units

If the values of force and length are increased four times, then the unit of energy will be increase by:

  1. 4 times

  2. 2 times

  3. 8 times

  4. 16 times
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The correct option is D
We have, $f=4[MLT^{-2}]$ and $d=4[L]$

$E=f\times d$

We know that Energy is equal to the product of force and distance.

Thus,
$=4[MLT^{-2}]\times4[L]$

$=16[ML^2T^{-2}]$

If both increased by 4times then the energy increased by $16\ times$
Multiple choice physics upthrust in fluids, archimedes' principle and floatation density of a fluid density of fluid density and relative density

A smooth rubber ball and a tennis ball some size are placed into two separated containers with the same amount of water in them. 
The ball will move more easily when both of them are spun at the same time?

  1. Smooth rubber ball

  2. Tennis ball

  3. Both will move more easily

  4. They do not move at all
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A smooth rubber ball has less surface friction than a tennis ball, which has a fuzzy texture. When spun in water, the tennis ball experiences more drag due to its surface texture, making the smooth ball move more easily.

Multiple choice physics force and newton's laws of motion inertia and mass concept of inertia galileo's law and inertia

The mass of object A is 5 kg,that of object B is 40 kg,that of object C is 38 kg,and that of object D is 56 kg. Which object has the greatest inertia?

  1. A

  2. B

  3. C

  4. D
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The object having the greatest mass has the greatest inertia because more force is required to change the initial state of the object.

Thus object D has the greatest inertia.

Multiple choice physics force and newton's laws of motion inertia and mass concept of inertia galileo's law and inertia

A and B are two objects with mass 6 kg and 34 kg respectively. Then,

  1. A has more inertia than B

  2. B has more inertia than A

  3. A and B both have same inertia

  4. None of the above statements is true
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mass of body is translation inertia. So, more mass means more inertia. (heavier body difficult to move)

So, option B is correct.

Multiple choice physics force and newton's laws of motion inertia and mass concept of inertia galileo's law and inertia

P and Q are two objects with masses 5 kg and 30 kg respectively. Then,

  1. P has more inertia than Q

  2. Q has more inertia than P

  3. P and Q have the same inertia

  4. Neither P nor Q has any inertia
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Mass is a translation inertia of body.

More mass means more inertia.
So, $ Q$ has more inertia than $P$.
Option B is correct.

Multiple choice physics force and newton's laws of motion inertia and mass concept of inertia galileo's law and inertia

$P$ and $Q$ are two objects with masses $5  kg$ and $30  kg$ respectively. Then

  1. $P$ has more inertia than $Q$
  2. $Q$ has more inertia than $P$
  3. $P$ and $Q$ have the same inertia
  4. Neither $P$ nor $Q$ has any inertia
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Inertia is the quality in matter (matter is anything you can touch) that lets it stay still if it is still, or keeps it moving if it is moving.

Since Q has more mass it has more inertia than P.

Multiple choice physics force and newton's laws of motion inertia and mass concept of inertia galileo's law and inertia

X and Y are two objects with masses $100\ kg$ and $75\ kg$ respectively, then :

  1. Both will have the same inertia

  2. Y will have more inertia

  3. X will have more inertia

  4. Both will have less inertia
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The object having more mass has more inertia and vice-versa.As object X has more mass than Y, thus X has more inertia.

Multiple choice physics nuclei nuclear force the nuclear force nuclear force and binding energy

A hydrogen atom having kinetic energy $E$ collides with a stationary hydrogen atom. Assume all motions are taking place along the line of motion of the moving hydrogen atom. For this situation, mark out the correct statement(s)

  1. For $E\ge20.4\space eV$ only, collision would be elastic
  2. For $E\ge20.4\space eV$ only, collision would be inelastic
  3. For $E = 2.4\space eV$, collision would be perfectly inelastic
  4. For $E = 18\space eV$, the $KE$ of initially moving hydrogen atom after collision is zero
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

K.E=2P.E
For electron in hydrogen to excite, a minimum of 10.2eV energy is required. Therefore, minimum 20.4eV K.E is required for inelastic collision otherwise, electron would not accept energy. And if E=20.4eV, collision would be perfectly inelastic.
If E is less than 20.4eV, collision is elastic and the two hydrogen atoms exchange velocities.
Therefore, B,D are the correct answers.

Multiple choice physics turning effects of forces stability and centre of mass center of mass centre of mass

Two bodies of masses 10 kg and 2 kg are moving with velocities $2\hat { i } -7\hat { k } +3\hat { j }\ m{ s }^{ -1 }$ and $-10\hat { i } +35\hat { k } -3\hat { j }\ m{ s }^{ -1 }$ respectively. The velocity of their centre of mass is

  1. $2\hat { i }\ m{ s }^{ -1 }$
  2. $2\hat { j }\ m{ s }^{ -1 }$
  3. $\left( 2\hat { j } +2\hat { k } \right) m{ s }^{ -1 }$
  4. $\left( 2\hat { i } +2\hat { j } +2\hat { k } \right) m{ s }^{ -1 }$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$m _1 = 10\ kg\quad \vec {v _1}=2\hat i -7\hat k+3\hat j\ m/s$
$m _2=2\ kg \quad \vec {v _2}=-10\hat i +35\hat k-3\hat j\ m/s$
velocity of centre of mass should be
$\vec {v}=\dfrac {m _1 \vec {v _1}+m _2 \vec {v _2}}{m _1 +m _2}$
or $\vec {v}=\dfrac {20\hat i-70\hat k+30\hat j+(-20\hat i+70\hat k-6\hat j)}{10+2}$
$\Rightarrow \ \boxed {\vec {v}=\dfrac {24\ \hat j}{12}=2\hat j\ m/s}$
Multiple choice power work and power work, energy and power physics energy and its forms

A body of mass $10kg$ is moving along positive $x-$axis with $5\ m/s$ at $t=0$ and is moving along negative $x-$axis with same speed at $t=10\ s$. Average power of the force acting on the body is:

  1. $Zero$
  2. $25\ W$
  3. $50\ W$
  4. $100\ W$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

since there is no acceleration 

there is no power
P=0

Multiple choice power work and power work, energy and power physics energy and its forms

An object of mass accelerates uniformly from rest to a speed $v _f$ in time $t _f$ Then the instantaneous power delivered to the object,as a function of time $t$ is -

  1. $mt\left(\dfrac{{v _f}^2}{t _f}\right)$
  2. $mt\dfrac{v _f}{t _f}$
  3. $\dfrac{1}{2}mt^2\left(\dfrac{v _f}{t _f}\right)^2$
  4. $\dfrac{1}{2}mt^2\left(\dfrac{v _f}{t _f}\right)$
Reveal answer Fill a bubble to check yourself
A Correct answer