Physics

Kinematics and Dynamics of Motion

121 Questions

Kinematics and dynamics explore projectile motion, inertia, free fall, and kinetic energy. These physics topics frequently appear in general science papers of major competitive exams. Practice these questions to understand the mechanical laws of motion.

Projectile motionFree fall calculationsInertia conceptsKinetic energyImpulse and collision

Kinematics and Dynamics of Motion Questions

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

A football rolls through the ground. The path followed by center of mass of football is:

  1. linear

  2. circular

  3. rotational

  4. all the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a football rolls through the ground, the path followed by center of mass of ball is linear as the center of mass remains always at a fixed height from the ground when the football rolls and moves in a straight line if the ball does not changes its direction of rolling which is assumed in this case.

The correct option is A.

Multiple choice physics force and types of force introduction to force what is force? concept of force and its unit

A ball of mass $400 \ gm$ is dropped from a height of $5 \ m$. A boy on the ground hits the ball vertically upwards with a bat with an average force of $100 N$ so that it attains a vertical height of $20 \ m$. Find the time for which the ball remains in contact with the bat.

  1. $0.12 s$
  2. $0.24 s$
  3. $0.36 s$
  4. $0.48 s$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$M=0.4 gm$ $=0.4 kg$

${h _1} = 5\,m$ $,$ ${h _2} = 20\,m$
$g = 10 \,m/{s^2}$
Velocity of the ball after dropping $5m:u$
Velocity of the ball after being hit by the bat$:v$
${u^2} = 2g{h _1} ; u = \sqrt {\left( {2 \times 10 \times 5} \right)}  = 10\,m/s\,\left( {downwards} \right)$

${v^2} = 2g{h _2} ;  \left( {2 \times 10 \times 20} \right) = v = 20\,m/s\left( {upwards} \right)$

Change of momentum $=$impulse$=$ $m(v+u)=12\,kg\,m/s$
Force$=100N=12/t$
$t=$ time of contact $=0.12sec$
Hence,
option $(A)$ is correct answer.

Multiple choice modelling collisions collisions momentum work, energy and power physics

A ball is dropped on the floor from a height of $10m$. It rebounds to a height of $2.5\ m$. If the ball is in contact with the floor for $0.01\ s$, then the average acceleration during contact is nearly.

  1. $500\sqrt {2}m/s^{2} upwards$
  2. $1800\sqrt {2}m/s^{2} downwards$
  3. $1500\sqrt {2}m/s^{2} upwards$
  4. $1500\sqrt {2}m/s^{2} downwards$
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice modelling collisions collisions momentum work, energy and power physics

A ball of mass 0.20 kg falls freely from a certain height and rebounds elastically with a speed of $40 \,ms^{-1}$. The change in momentum of the ball is :

  1. $4\,kg \,ms^{-1}$
  2. $8\,kg \,ms^{-1}$
  3. $16\,kg \,ms^{-1}$
  4. $40\,kg \,ms^{-1}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Change in momentum, $\Delta p =- 2mv$
$= 2 \times 0.2\times 40 = 16 kg ms^{-1}$(magnitude)

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

A rain drop of mass $0.1g$ is falling with uniform speed of $10{ cm/s }$. What is the net force the drop?

  1. ${ 10 }^{ -2 }N$
  2. ${ 10 }^{ -3 }N$
  3. $2\times { 10 }^{ -3 }N$
  4. $zero$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Uniform speed means that a body is traveling at a constant speed along a straight line. So it has no acceleration. Thus net weight $=ma=0$.

Multiple choice physics force and newton's laws of motion first law of motion newton's first law of motion momentum and newton's laws

A person sitting in an open car moving at constant velocity throws a ball vertically up into air. Where will the ball fall?

  1. Outside the car

  2. In the car ahead of the person

  3. In the car to the side of the person

  4. Exactly in the hand from which it was thrown up
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ball has forward velocity equal to the velocity of the car even when ball is given velocity upwards.

So, the ball will cover the same distance as that by the car, and hence it will land in the hands of the person.

Multiple choice physics simple harmonic motion a few applications of linear shm simple pendulum example of simple harmonic motion

If a tunnel is cut at any orientation through earth, then in what time will, a ball released from one end, reach the other end (neglect the rotation of the earth) ?

  1. 84.6 minutes

  2. 42.3 minutes

  3. 8 minutes

  4. depends on orientation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Force and to rque 
As we know
g depth = $g\left ( 1-\frac{d}{R} \right )$
$g _{d} = g\left ( \frac{R-d}{R} \right )\because (R-d)=x$
$g _{d}=\frac{g}{R}x$
$F _{r}=-mg _{d}$
$F _{R}=\frac{-mgx}{R}\Rightarrow F = -KX$
$T = 2\pi \sqrt{\frac{m}{k}}\rightarrow $ As we know
$K = \frac{mg}{R}$
$T= 2\pi \sqrt{\frac{mR}{mg}}$
$T= 2\pi \sqrt{\frac{R}{g}}$
$T = 84.6 ,minutes $
$A\rightarrow B;t=\frac{T}{2}=\frac{84.6}{2}=43.2$
Multiple choice physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

A stone is dropped from the top of a tower of $125m$ high into a pond which is at base of the tower. When will the splash be heard at the top? (Given $g = 10ms^{-1}$ and speed of sound $=340ms^{-1}.$)

  1. $5s$
  2. $0.36s$
  3. $5.36s$
  4. $2s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Time to fall: h = 0.5 * g * t^2 -> 125 = 5 * t^2 -> t^2 = 25 -> t = 5s. Time for sound to travel up: t2 = h / v = 125 / 340 = 0.367s. Total time = 5 + 0.367 = 5.367s.

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A ball of mass 50 g is thrown upwards. It rises to a maximum height of 100 m. At what height its kinetic energy will be reduced to 70%?

  1. 30 m

  2. 40 m

  3. 60 m

  4. 70 m
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

By work energy theorem,

$U _i+K _i=U _f+K _f$
$0+K _i=mgh+0$
$K _i=(50\times10^{-3})(10)(100)J$
$K _i=50J$ $-(i$)
Now, we have $K _f=\dfrac{70}{100}K _i$
By work energy theorem,
$0+K _i=mgh+\dfrac{70}{100}K _i$
$K _i-\dfrac{70}{100}K _i=(50\times10^{-3})(10)(h)$
$\dfrac{30}{100}K _i=0.5h$
From $(i)$, we have $K _i=50$
$h=2\times\dfrac{30}{100}\times50m$
$h=30m$

Multiple choice physics force concept of force and its unit force - push or pull forces

A 200 g of putty ball falls vertically into a 2.5 kg cart that is rolling freely at 2 m/s on a horizontal surface. What is the final speed of the cart?

  1. $11.85 m/s$
  2. $1.85 m/s$
  3. $10.85 m/s$
  4. $2.85 m/s$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Using conservation of momentum: m1 * v1 + m2 * v2 = (m1 + m2) * v_final. Here, 2.5 * 2 + 0.2 * 0 = (2.5 + 0.2) * v_final. 5 = 2.7 * v_final. v_final = 5 / 2.7 = 1.8518 m/s.

Multiple choice maths geometric sequences sum of terms of g.p sum of n terms of an gp summing geometric series

A rubber ball is dropped from a height of $10$ meters. If the ball always rebounds $\dfrac {4}{5}$ the distance it has fallen, calculate, how far, in meters, will the ball have travelled at the moment it hits the ground for the fourth time?

  1. $4.10$
  2. $5.12$
  3. $29.52$
  4. $43.92$
  5. $49.04$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation
  • for the first time it hits the ground , it travels $10$ m
  • for the second time it hits the ground , it travels $2 \times 4/5 \times 10 = 16+10 =26$
  • for the third time it hits the ground , it travels $ 2\times 4/5 \times 4/5 \times 10 +26 =64/5+26 = 38.8$
  • for the fourth time it hits the ground , it travels $2 \times 4/5 \times 4/5 \times 4/5 \times 10 +38.8 = 256/25 + 38.8 =49.04$

Multiple choice physics lever common machines terms related to machines introduction to simple machines

A rubber ball dropped from a height of $20\ m (g = 10\ m/s^{2})$ falls on the roof of an elevator going up at $2\ m/s$. If the collision of the ball with the elevator is elastic, the ball rebounds with a velocity of

  1. $20\ m/s$
  2. $22\ m/s$
  3. $24\ m/s$
  4. $26\ m/s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Velocity of ball before impact: v = sqrt(2gh) = sqrt(2 * 10 * 20) = 20 m/s (downward). Elevator velocity = 2 m/s (upward). Relative velocity of ball w.r.t elevator = 20 - (-2) = 22 m/s. After elastic collision, it rebounds at 22 m/s relative to the elevator. Absolute velocity = 22 + 2 = 24 m/s.

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

A metal ball of mass $2kg$ is allowed to fall freely from rest from a height of $5m$ above the ground (Take $g=10ms^{-2}$). After the ball hits the ground and comes to rest, mechanical energy is converted to:

  1. heat energy

  2. sound energy

  3. electrical energy

  4. Both A & B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When ball is at rest it will have only P.E that is
$P.E = mgh$


$m = 2\  kg; h = 5\  m$

$P.E = 2\times 10\times 5 = 100 J$

This is the total energy as K.E is zero when ball is at maximum height that is when it is at 5m. Hence when ball reaches the ground P.E becomes zero  because height is zero. At this point total energy is equal to K.E that is $K.E = 100 J$.

This $100\  J$ will convert to heat and sound energy as the ball comes to rest.