Physics · Science General

Collisions, Momentum and Kinetic Energy

331 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

Which of the following statements is true?

  1. Kinetic energy and momentum both are conserved in all types of motion.

  2. Momentum is conserved in elastic collision but not in inelastic collision.

  3. Total kinetic energy is not conserved but momentum is conserved in inelastic collision.

  4. All the above are correct.
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice

In E = mc, m is

  1. mass

  2. velocity

  3. acceleration

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Einstein's mass-energy equivalence formula E = mc^2, m represents mass and c represents the speed of light.

Multiple choice

If the momentum of a body is doubled, the kinetic energy ___________.

  1. becomes halved

  2. gets doubled

  3. remains unchanged

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

Yes, it is correct. Momentum  = M * V is directly proportional to velocity and kinetic energy is proportional to square of velocity. If the velocity is doubled,  the momentum is doubled and and kinetic energy becomes four times.

Multiple choice physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

If units of mass and length are doubled and that of time remains same, in which quantity numberical value is unchanged?

  1. Force

  2. Energy

  3. Power

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

Stress is defined as force per unit area (Force/Area). If mass and length are doubled, Force (MLT^-2) scales by 2*1*1^-2 = 2, and Area (L^2) scales by 2^2 = 4. Stress scales by 2/4 = 0.5, which changes. However, in many physics contexts, if units are changed proportionally, dimensionless quantities or specific ratios remain unchanged; checking the dimensions, Stress is M L^-1 T^-2. If M -> 2M and L -> 2L, the new value is (2M)(2L)^-1 T^-2 = (2/2) M L^-1 T^-2 = 1. Thus, the numerical value remains unchanged.

Multiple choice

What formula is used to calculate total mechanical energy (TME)?

  1. TME = Kinetic Energy + Potential Energy

  2. TME = Kinetic Energy x Potential Energy

  3. TME = Kinetic Energy ÷ Potential Energy

  4. TME = Kinetic Energy x Potential Energy x Gravity
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total mechanical energy is defined as the sum of an object's kinetic energy and its potential energy at any given time.

Multiple choice physics kinematics motion around us motion and rest moving things around us

Two balls of different masses have the same KE. Then the: 

  1. Heavier ball has greater momentum than the lighter ball.

  2. Lighter Will has greater momentum than the heavier ball.

  3. Both bans have equal momentum.

  4. Both balls have zero momentum.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The relation between kinetic energy $(K)$ and momentum $(p)$ is given by, $K=\dfrac{p^2}{2m}$ where $m$ be the mass of the body

So, $p=\sqrt{2mK}$
As kinetic energy is constant, so $p\propto \sqrt m$
Thus, the heavier ball has more momentum than that of lighter ball. 

Multiple choice chemistry nuclear physics types of radioactivity nuclear chemistry and radioactivity radioactivity

Fill in the blanks :

The mass of a body remains constant till the velocity of body is ............

  1. much less than the velocity of light

  2. equal to velocity of light

  3. much higher than the velocity of light

  4. none of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Einstein if a body moves almost more than the velocity of light then it starts losing its mass.He gave this concept by a formula that is $E=m c^{2}$.Hence for the body to maintain constant mass it has to move with the speed less than the velocity of light.

Multiple choice lorentz transformation and muon experiment option a: relativity physics

If the speed of a rod moving at a relativistic speed parallel to its length is doubled,

  1. the length will become half of the original value

  2. the mass will become double of the original value

  3. the length will decrease

  4. the mass will increase
Reveal answer Fill a bubble to check yourself
C,D Correct answer
Explanation

Let the rest mass and rest length of the rod be $m _o$ and $L _o$, respectively.

According to relativity, length of the moving object parallel to its motion (or velocity) gets reduced by a factor of $\sqrt{1 - \dfrac{v^2}{c^2}}$ of its rest length but its mass gets increased by the same factor.
$\therefore$ Parallel length of the moving object         $L _{\parallel}  =L _o \sqrt{1-\dfrac{v^2}{c^2}}$         $\implies L _{\parallel} < L _o$
Also mass of the moving object         $m  =\dfrac{m _o}{ \sqrt{1-\dfrac{v^2}{c^2}}}$                $\implies m>m _o$
Hence options C and D are correct.

Multiple choice relativistic mechanics option a: relativity physics

Two masses of 1g and 4g are moving with equal K.E. The ratio of the magnitude of their linear momentum is-

  1. 1 : 1

  2. 1 : 2

  3. 1 : 3

  4. 1 : 4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kinetic energy K = p^2 / (2m), so momentum p = sqrt(2mK). Since K is equal for both, the ratio of momenta p1/p2 = sqrt(m1/m2) = sqrt(1/4) = 1/2.

Multiple choice relativistic mechanics option a: relativity physics

As the speed of a particle increases, its rest mass

  1. increases

  2. decreases

  3. remains the same

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

Rest mass $(m _o)$ is defined as the mass of the object at rest (or in rest frame) which remains constant.

Only the mass of the moving object changes as the speed increases  via   $m  = \dfrac{m _o}{\sqrt{1-\dfrac{v^2}{c^2}}}$
Hence option C is correct.

Multiple choice relativistic mechanics option a: relativity physics

If $M$ and $m$ are moving mass and rest mass respectively of a body and $c$ is speed of light,

then kinetic energy of body is given by :

  1. $K = [m - M]c^2$
  2. $K = [M - m]c^2$
  3. $K = Mc^2$
  4. $K = mc^2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Kinetic energy in relativistic mechanics is the difference between total energy (Mc^2) and rest energy (mc^2), which simplifies to (M - m)c^2.

Multiple choice relativistic mechanics option a: relativity physics

By what fraction does the mass of a boy increase when he starts running at a speed of 12 km h$^{-1}$?

  1. $11\times {10}^{-27}$
  2. $20\times {10}^{-27}$
  3. $6.17\times {10}^{-27}$
  4. $25.89\times {10}^{-27}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Given :   $v = 12$ km/h $ = 12\times \dfrac{5}{18}  =3.33$  m/s

Mass of the boy while running       $m  =\dfrac{m _o}{\sqrt{1 - (\frac{v^2}{c^2})^2}}$
$\therefore$  Fractional increase in the mass         $\dfrac{\Delta m}{m _o} = \dfrac{\dfrac{m _o}{\sqrt{1- (v/c)^2}} - m _o}{m _o}  = [1-(v/c)^2]^{-1/2} - 1$
$\implies $     $\dfrac{\Delta m}{m _o} = 1+ \dfrac{v^2}{2c^2}  -1  = \dfrac{v^2}{2c^2}$               (for $ v<< c$)

$\therefore$    $\dfrac{\Delta m}{m _o}  = \dfrac{3.33^2}{2 (3\times 10^8)^2}   =6.17\times 10^{-17}$  kg