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

If a boy sitting iii a railway train, moving at constant velocity, throws a ball straight up into the air,

  1. the ball will fall in front of him.

  2. the ball will fall behind hands.

  3. the ball will fall into his hand.

  4. the ball will not return downwards.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a boy throws a ball straight up in a train moving at a constant velocity, the ball retains the horizontal velocity of the train due to inertia. Relative to the boy, the ball only has vertical motion, so it will fall back into his hand. If the train were accelerating or decelerating, the ball would fall in front of or behind him.

Multiple choice

Which falls down faster in a vacuum a feather, a wooden ball or a steel ball?

  1. A wooden ball

  2. A feather

  3. A steel ball

  4. All will fall at the same speed.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a vacuum, air resistance is absent. According to Galileo's principle, all objects accelerate at the same rate due to gravity regardless of their mass. A feather, wooden ball, and steel ball will all fall with identical acceleration and hit the ground simultaneously.

Multiple choice

Which falls down faster in a vaccum?

  1. A wooden ball

  2. A steel ball

  3. A feather

  4. All will fall down at the same speed because there will be no air resistance
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a vacuum, there is no air resistance to oppose the motion of falling objects. According to the laws of physics, all objects fall with the same acceleration due to gravity regardless of their mass.

Multiple choice vedic methods of multiplication history of mathematics maths

Victor can throw a ball 50$\displaystyle{\dfrac{3}{5}}$ feet. Parth can throw the same ball 48$\displaystyle{\dfrac{1}{3}}$ feet. How much farther can Victor throw the ball than Parth ? 

  1. 2$\displaystyle{\dfrac{2}{15}}$ feet
  2. 2$\displaystyle{\dfrac{4}{15}}$ feet
  3. 2$\displaystyle{\dfrac{3}{5}}$ feet
  4. 2$\displaystyle{\dfrac{4}{5}}$ feet
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Victor can throw a ball $=50\dfrac{3}{5}$ feet

Parth can throw the same ball $=48\dfrac{1}{5}$ feet

Difference,
$=50\dfrac{3}{5}-48\dfrac{1}{3}$
$=\dfrac{253}{5}-\dfrac{145}{3}$
$=\dfrac{253}{5}-\dfrac{145}{3}$
$=\dfrac{34}{15}$
$=2\dfrac{4}{15}$ feet

Hence, this is the answer.

Multiple choice maths compound measures and motion kinetic graphs time - calcuation of distance travel graphs

Two bodies $A$ and $B$ are projected vertically up from the ground simultaneously. They spend $6$ seconds and $9$ seconds in air respectively. Raio of the maximum heights reached by them is

  1. $2:3$
  2. $6:9$
  3. $12:27$
  4. $4:9$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Let $A$ and $B$ have initial velocity as it $\mu _{2}$
As from Newtons first law of motion, $\upsilon = \mu t$ at
$\Rightarrow 0 = \mu _{1}- g t _{1} \Rightarrow t _{1} \dfrac{\mu _{1}}{g} (\upsilon = 0$ at top)
Similarly $t _{2}= \dfrac{\mu _{2}}{g}$
Now, from third law, $S= \dfrac{\upsilon^{2} - \mu^{2} }{2a}$
$\Rightarrow h ,  \dfrac{0-4^{2} _{1}}{-2g}= \dfrac{4 _{1}^{2}}{2g}= \dfrac{t _{1}^{2} g^{2} }{2g}= \dfrac{t _{1}^{2} g}{2}$
Similarly $h _{2}= \dfrac{t _{2}^{2} 9}{2} \Rightarrow \dfrac{h}{h _{2}}= \left( \dfrac{t _{1}}{t _{2}} \right)^{2} = \left( \dfrac{6}{9} \right)^{2}= \dfrac{4}{9}$
$\Rightarrow  (D)$
Multiple choice physics accelerated motion calculus methods of motion equations equation of motion the equation of motion and its derivation

An open lift is moving upwards with velocity $10m/s$. It has an upward acceleration of $2m/{s^2}$. A ball is projected upwards with upwards with velocity $20m/s$ relative to the ground. Find the time when the ball again meets the lift.

  1. $\frac{5}{3}s$
  2. $\frac{4}{3}s$
  3. $\frac{3}{4}s$
  4. $\frac{1}{4}s$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Let the time of Height of the ball be $t$. Then. with respect to the lift.
$V _{B/L}= V _{B}-V _{L}= 20-10= 10\ m/s$
$a _{B/L}=a _{B}-a _{L}=(-10)-(2)=-12\ m/s^{2}$
To find $t$, applying second $eq^{n}$ to motion 
$h =u (t)+ at^{2}$
$\Rightarrow o= (10)(t)+ \dfrac{(-12)t^{2}}{2}$
$\Rightarrow bt^{2}=10 t$
$\Rightarrow t = 5/3^{3}$
Option $-A$ is correct. 
Multiple choice lorentz transformation and muon experiment option a: relativity physics

Imagine an unlikely situation where a cannon fires a cannon ball at $(0.7)c$ (seventy percent of the speed of light) relative to a train to which the cannon is attached. The train is moving at $(0.6)c$ (sixty percent of the speed of light) relative to the ground.
If an observer on the ground measured the speed of the cannon ball relative to the ground, what speed would he measure?

  1. Exactly $c$
  2. $(1.3)c$
  3. $(0.7)c$
  4. $(0.6)c$
  5. Between $(0.7)c$ and $c$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Speed of train w.r.t ground       $v = 0.6c$

Speed of cannon ball w.r.t train      $v '  = 0.7 c$
According to relativity,  speed of cannon ball w.r.t ground       $v'' = \dfrac{v+v'}{1+vv'}$  
$\therefore$    $v'' = \dfrac{0.6c + 0.7c}{1 + (0.6c)(0.7c)} = \dfrac{1.3c}{1.42} = 0.915 c$

Multiple choice properties of magnet magnetic field moving charges and magnetism magnetic effects of current and magnetism physics neutral points magnetic poles and magnetic compass

If we go inside a mine and drop a $104 lb$  iron ball and $1$ lb aluminum ball from the top of a high platform, neglecting air resistance.

  1. Both will reach the floor at the same time
  2. $1$ lb weight will reach the floor first
  3. $10$ lb weight will reach the floor first

  4. It is not possible to indicate which of the two will reach the floor first without further data
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In real life the one having less volume and more weight will reach first

but in ideal situation where viscosity of air is neglected both will hit ground at same time irrespective of their masses if dropped from the same height 

this is because the acceleration produced due to gravity does not depend on the body.


Multiple choice physics work, energy and power collision of two rigid bodies energy and collisions understanding collisions

A plastic ball falls from a height of $4.9$ metre and rebounds several times from the floor. What is the coefficient of restitution during the impact with the floor if $1.3$ seconds pass from the first impact to the second one?

  1. $0.9$
  2. $0.1$
  3. $0.7$
  4. $0.8$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
As, $ t = \sqrt{\dfrac{2h}{g}} $
Velocity of ball just before collision $ = v = \sqrt{2gh} $
After first collision,
Velocity $ = v _{1} = ev = e\sqrt{2gh} $
So, $ t _{1} = \dfrac{v _{1}}{g} = e \sqrt{\dfrac{2h}{g}} $
So, time for second collision will be 
$ T = t+2t _{1} $
$ = (1+2e)\sqrt{\dfrac{2h}{g}} $
Putting, $ T = 1.3\,sec.,h = 4.9\,m $
$ 1.3 = (1+2e)\sqrt{\dfrac{2\times 4.9}{9.8}} $
$ 1.3 = 1+2e $
$ 0.3 = 2e $
$ \boxed{e = 0.1} $