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 along with motion what forces can do? force and it's unit force and its effects

Two bodies of masses ${m} _{1}$ and ${m} _{2}$ are acted upon by a constant force $F$ for a time $t$. They start from rest and acquire kinetic energies ${E} _{1}$ and ${E} _{2}$ respectively. Then $\dfrac{{E} _{1}}{{E} _{2}}$ is

  1. $\dfrac{{m} _{1}}{{m} _{2}}$
  2. $\dfrac{{m} _{2}}{{m} _{1}}$
  3. $1$
  4. $\dfrac{\sqrt{{m} _{1}{m} _{2}}}{{m} _{1}+{m} _{2}}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bodies of mass $m _1$ and $m _2$ acted on by force F (say) for time t. Acceleration in mass $m _1$= $\dfrac{F}{m _1}$
Acceleration in mass $m _2$= $\dfrac{F}{m _2}$
Velocity acquired during this time for mass $m _1$
$v _1=\dfrac{F}{m _1} t$
Velocity acquired during this time for mass $m _2$
$v _2=\dfrac{F}{m _2} t$

Ratio of kinetic energy acquired
$\dfrac{E _1}{E _2}=\dfrac{\dfrac{1}{2}m _1v _1^2}{\dfrac{1}{2}m _2v _2^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _1\times (\dfrac{F}{m _1} t)^2}{m _2\times (\dfrac{F}{m _2} t)^2}$
$\dfrac{E _1}{E _2}=\dfrac{m _2}{m _1}$

Multiple choice physics static electricity explaining static electricity charging by induction electric charges and fields

Two bodies are changed by rubbing one against the other. During the process, one becomes positively charged while the other becomes negatively charged. Then,

  1. mass of each body remains unchanged.

  2. mass of each body changes marginally.

  3. mass of each body changes slightly and hence the total mass.

  4. mass of each body changes slightly but the total mass remains the same.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
The transfer of electrons from one body to the result in redistribution of charges.
Hence, no. of electrons given by one body $=$ Number of electrons obtained by the other.
$\therefore$ Mass of negatively charged body slightly increases.
Whereas the total mass of the system remain the same.
Multiple choice physics rotational motion of a rigid body and moment of inertia angular momentum (l) and conservation of angular momentum angular momentum in case of rotation about a fixed axis law of conservation of angular momentum

 Two bodies of different masses have same K.E. The one having more momentum is

  1. Heavier body

  2. lighter body

  3. both none

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

$K.E.$ for a given momentum is inversely proportional to the mass$.$

So$,$ the lighter mass has greater kinetic energy$.$ For two bodies having same kinetic energy$,$ the heavier one has greater momentum$.$
Hence,
option $(B)$ is correct answer.  

Multiple choice physics rotational motion of a rigid body and moment of inertia angular momentum (l) and conservation of angular momentum angular momentum in case of rotation about a fixed axis law of conservation of angular momentum

A stationary body explodes into two fragments of masses ${m} _{1}$ and ${m} _{2}$. If momentum of one fragment is $p$, the minimum energy of explosion is

  1. $\cfrac { { p }^{ 2 } }{ 2\left( { m } _{ 1 }+{ m } _{ 2 } \right) } $
  2. $\cfrac { { p }^{ 2 } }{ 2\left( \sqrt { { m } _{ 1 }{ m } _{ 2 } } \right) } $
  3. $\cfrac { { p }^{ 2 }\left( { m } _{ 1 }+{ m } _{ 2 } \right) }{ 2{ m } _{ 1 }{ m } _{ 2 } } $
  4. $\cfrac { { p }^{ 2 } }{ 2\left( { m } _{ 1 }-{ m } _{ 2 } \right) } $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Initially body is stationary (zero velocity)

using conservation of momentum
$\left( A \right) O=P+{ P _{ 2 } },{ P _{ 2 } }$ is momentum of mass ${m _2}$ after explosion
$\begin{array}{l} { P _{ 2 } }=-P \ Energy={ E _{ 1 } }\Rightarrow \dfrac { { { P^{ 2 } } } }{ { 2{ m _{ 1 } } } } d{ E _{ 2 } }=\dfrac { { { { \left( { -P } \right)  }^{ 2 } } } }{ { 2{ m _{ 2 } } } }  \ net\, \, energy\Rightarrow { E _{ 1 } }+{ E _{ 2 } }=\dfrac { { { P^{ 2 } } } }{ { 2{ m _{ 2 } } } } +\dfrac { { { P^{ 2 } } } }{ { 2{ m _{ 2 } } } } \Rightarrow \dfrac { { { P^{ 2 } } } }{ { 2\left( { { m _{ 1 } }+{ m _{ 2 } } } \right)  } }  \end{array}$

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

A body off mass $5kg$ falls from a height of $30metre$. If its all mechanical energy is changed into heat, then heat produced will be 

  1. $ \text{350 cal} $
  2. $ \text{150 cal} $
  3. $ \text{60 cal} $
  4. $ \text{6 cal} $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Potential energy = mgh = 5 * 9.8 * 30 = 1470 Joules. Since 1 calorie is approximately 4.2 Joules, 1470 / 4.2 = 350 calories.

Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Using $E = m{c}^{2}$, find out the energy released, when $2  u$ of mass is destroyed completely.
Take $1  u = 1.66 \times {10}^{-27}  kg$.

  1. $4.65 MeV$
  2. $3627 MeV$
  3. $91.5 MeV$
  4. $1865 MeV$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
When $2u$ of mass is destroyed completely then
$\triangle m=2u\\ E=\triangle m{ c }^{ 2 }\\ E=2\times 931MeV\\ \therefore 1u=931Mev/{ c }^{ 2 }\\ So,E=1863MeV\approx 1865MeV$
So, (D) is correct option.
Multiple choice nuclear reactions nuclear structure nuclei atomic nuclei physics

Energy released if mass of $2\ amu$ is converted into energy is :

  1. $1.5 \times 10^{-10}\ J$
  2. $3 \times 10^{-10}\ J$
  3. $1863\ J$
  4. $931.5 \Mev$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$ E = \Delta m c^{2}$
    $ = (2 \times 1.67 \times 10^{-27}  kg) \times (3 \times 10^{8} \frac{m}{s})^{2} $
    $ = 3 \times 10^{-10}  J$

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

Which of the following statements are true?

  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.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
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.