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

A force $'F'$ accelerates a block of mass $'m'$ along a straight line to velocity $'v'$ from rest and displace it through a distance $'s'$. What is the average power developed?

  1. $\dfrac {v^{2}}{2F}$
  2. $Fv$
  3. $\dfrac {mv^{2}}{2s}$
  4. $\dfrac {Fv}{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

For constant acceleration starting from rest, v_avg = v / 2. Average Power = F * v_avg = F * (v / 2).

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

A block of mass $1$ $kg$ starts moving with constant acceleration $\displaystyle a= 4m/s^{2}.$. Find the average power of the net force in a time interval from $t=0$ to $t=2s$.

  1. $16 W$
  2. $1.6 W$
  3. $15 W$
  4. $1.5 W$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Velocity of an object after time $t$ is given by $v=at$
Average power from time $t _1$ to $t _2$

$=\dfrac{\int _{t _1}^{t _2}Fvdt}{\int _{t _1}^{t _2}dt}$

$=\dfrac{\int _0^t(ma)(at)dt}{\int _0^tdt}$

$=ma^2\dfrac{t}{2}$

$=1\times 4^2\times\dfrac{2}{2}W$

$=16W$
Multiple choice power work and power work, energy and power physics energy and its forms

A $40 N$ force accelerates a $20 kg$ mass through a distance of $16 m$. If there were no other forces acting on the mass and the mass started at rest, what was the average power output of the force?

  1. $0 W$
  2. $160 W$
  3. $226 W$
  4. $640 W$

  5. Cannot be determined from the information given
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given :  $F = 40$ N            $m = 20$ kg              $S = 16$ m               $u = 0$ m/s

Thus acceleration of the mass        $a = \dfrac{F}{m} = \dfrac{40}{20} =2$  $m/s^2$
Using    $S = ut + \dfrac{1}{2}at^2$
$\therefore$  $16 = 0 + \dfrac{1}{2} \times 2 t^2$                      $\implies t = 4$ s
Work done by the force     $W = FS = 40 \times 16  =640$ J
$\therefore$ Power output        $P = \dfrac{W}{t} = \dfrac{640}{4} = 160$  W

Multiple choice physics energy : forms and sources concept of energy energy for everything forms of energy

What will be the potential energy of a body of mass 5 kg kept at a height of 10 m ?

  1. 50 J

  2. 0.5 J

  3. 500 J

  4. 25 J
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Answer is C.

Potential energy is energy stored in an object. This energy has the potential to do work. Gravity gives potential energy to an object. This potential energy is a result of gravity pulling downwards. The gravitational constant, g, is the acceleration of an object due to gravity. This acceleration is about 10 meters per second on earth. The formula for potential energy due to gravity is PE = mgh. As the object gets closer to the ground, its potential energy decreases while its kinetic energy increases. 
In this case, a body of mass 5 kg kept at a height of 10 m. So the potential energy is given as 5 * 10 *10 = 500 J.
Hence, the potential energy of a body of mass 5 kg kept at a height of 10 m is 500 J.

Multiple choice physics energy : forms and sources concept of energy energy for everything forms of energy

An object of mass $40\ kg$ is raised to a height of $5\ m$ above ground. If the object is allowed to fall down find its kinetic energy when it is half-way down.

  1. 1960 J

  2. 980 J

  3. 990 J

  4. 1000 J
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Gravitational Potential energy, $W = mgh$

$h=$ vertical displacement $=5\ m$

$m =$ Mass of object $= 40\ Kg$

$g =$ Acceleration due to gravity $= 9.8\ ms^{-2}$

$W = 40 \times 5 \times 9.8= 1960\ J$

For half way down$=\dfrac{1960}{2}= 980\ J$

At this point i.e. half way object has an equal amount of potential and kinetic energy.

Multiple choice physics energy : forms and sources concept of energy energy for everything forms of energy

If the values of force and length are increased four times then the unit of energy will increases 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

 Force is represented as $\left[ ML{ T }^{ -2 } \right] \quad and\quad length\left[ L \right] $

$energy\quad f\times d\quad is\left[ ML{ T }^{ -2 } \right] \quad \times \left[ L \right] =\left[ M{ L }^{ 2 }{ T }^{ -2 } \right] $
 if Force and length are quadrupled in value Energy
$4\left[ ML{ T }^{ -2 } \right] \quad \times 4\left[ L \right] =16\left[ M{ L }^{ 2 }{ T }^{ -2 } \right] $
unit increased by 16 times 

Multiple choice physics physical quantities and measurement measurement of small and large distances measurement of distance unit of fundamental quantities

Which of the following defines 1 kg of mass correctly?

  1. When a force of 1N produced an acceleration of $\displaystyle 1{ m }/{ { s }^{ 2 } }$ in a body, then the mass is said to be 1 kg
  2. When a force of 10N produced an acceleration of $\displaystyle 10{ m }/{ { s }^{ 2 } }$ in a body, then the mass of body is said to be 1 kg
  3. When a force of 100N produced an acceleration of $\displaystyle 1{ m }/{ { s }^{ 2 } }$ in a body, then the mass of body is said to be 1 kg

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

When a force of 1 N produced an acceleration of $\displaystyle 1{ m }/{ { s }^{ 2 } }$ in a body, then the mass of body is said to be 1 kg.(definition)

Multiple choice physics the essence of change forms of energy and energy conservation energy for everything forms of energy

A body $A$ is placed on a railway platform and an identical body $B$ in a moving train. Which of the following energies of $B$ are greater than those of $A$ as seen from the ground?

  1. Kinetic

  2. Total

  3. Mechanical

  4. Internal
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Since the body B is in a moving train, it will have higher kinetic energy as compared to the body on platfrom. It is because the speed of the body $A$ is zero.

The total energy of the body $B$ will be more than body $A$ due to its state of motion and the mechanical energy of the body $B$ will be higher due to more amount of work done on it as it is moving.

The internal energy of the two identical bodies do not depend on other external factors and it remains constant for the bodies.

So, only the internal energy will not change.

Multiple choice physics universe and space heliocentric model introduction to gravitation introduction to gravity

Gravitational unit of force produce an acceleration in a body equal to 

  1. $g$
  2. $0$
  3. $2g$

  4. unit value
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Acceleration due to gravity is denoted by '$g$'.
A force which produces an acceleration in a body equal to acceleration due to gravity on earth, when the body has a unit mass is called gravitational unit of force.