Physics

Kinematics and Dynamics of Motion

128 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 collisions in one dimension collisions work, energy and power mechanics physics

A rubber ball is bounced on the floor of a room which has its ceiling at a height of  $3.2{ m }$  from the floor. The ball hits the floor with a speed of  $10 m / { s },$  and rebounds vertically up. If all collisions simply reverse the velocity of the ball, without changing its speed, then how long does it take the ball for a round trip, from the moment it bounces from the floor to the moment it returns back to it ? Acceleration due to gravity is  $10 m / s ^ { 2 }.$

  1. $4 s$
  2. $2 s$
  3. $0.8 s$
  4. $1.2 s$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The time taken to reach the highest point after the rebound at speed v = 10 m/s is t_up = v/g = 10/10 = 1 s. However, the ceiling is at a height of 3.2 m. Using kinematic equation y = v*t - (1/2)*g*t^2, at y = 3.2m we get 3.2 = 10*t - 5*t^2, which solves to t = 0.4 s (the ball hits the ceiling before reaching its natural peak of 5m). The collision with the ceiling reverses the velocity, so the round trip time until it returns to the floor is 0.8 s.

Multiple choice collisions in one dimension collisions work, energy and power mechanics physics

A perfectly elastic ball falls on a horizontal floor from a height in a time $t$. It will hit the floor again after a time $t'$. The ratio of $t'$ and t is 

  1. $1:1$
  2. $1:2$
  3. $2:1$
  4. $1:4$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A ball falling freely from height h takes time t = sqrt(2h/g) to reach the floor. For a perfectly elastic collision, it rebounds with the same speed and takes the same time t to return to the original height. The total time elapsed before it hits the floor again is t' = 2t, making the ratio t' to t equal to 2:1.

Multiple choice collisions in one dimension collisions work, energy and power mechanics physics

A ball is dropped from height h on the ground. If the coefficient of restitution is e, the height to which the ball goes up after it rebounds for the nth time is :

  1. $\dfrac{h}{e^{2n}}$
  2. $\dfrac{e^{2n}}{h}$
  3. $he^{2n}$
  4. $he^n$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Let $v _0$ be the velocity with which the ball strikes the Earth first time and $v _n$ after the nth rebound.
The coefficient of restitution is
$e=\dfrac{v _1}{v _0}=\dfrac{v _2}{v _1}=\dfrac{v _3}{v _2}=$.....$=\dfrac{v _n}{v _{n-1}}$
$\therefore e^n=\dfrac{v _1}{v _0}\times \dfrac{v _2}{v _1}\times\dfrac{v _3}{v _2}\times $.....$\times \dfrac{v _n}{v _{n-1}}=\dfrac{v _n}{v _0}$
Here, $v _0=\sqrt{2gh}$ and $v _n=\sqrt{2gH}$
$e^n=\dfrac{\sqrt{2gH}}{\sqrt{2gh}}=\dfrac{\sqrt{H}}{\sqrt{h}}$
$e^{2n}=\dfrac{H}{h}\Rightarrow H=he^{2n}$
Multiple choice

Tiffany throws a ball up in the air. Why does the ball come back down?

  1. Tiffany is pulling the ball down.

  2. Air is pushing the ball down.

  3. Gravity is pulling the ball down.

  4. Gravity is pushing the ball away from Tiffany.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gravity is the fundamental force of attraction that pulls objects toward the center of the Earth. When a ball is thrown upward, gravity acts to decelerate it and eventually pull it back down to the ground.

Multiple choice

What is the scientific term for the sudden stop of a breakdancer's movement?

  1. Deceleration

  2. Friction

  3. Impulse

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

Impulse is the product of force and time. When a breakdancer suddenly stops their movement, a large impulse is applied to their body, causing them to decelerate rapidly.

Multiple choice

A soccer player kicks a ball with an initial velocity of 20 m/s at an angle of 45 degrees to the horizontal. What is the maximum height reached by the ball?

  1. 10 meters

  2. 15 meters

  3. 20 meters

  4. 25 meters
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The maximum height reached by the ball can be calculated using the formula: h = (v^2 * sin^2(theta)) / (2 * g), where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: h = (20^2 * sin^2(45)) / (2 * 9.81) = 15 meters.

Multiple choice

A baseball player hits a ball with a bat, giving it an initial velocity of 30 m/s at an angle of 30 degrees to the horizontal. If the ball is hit at a height of 1 meter above the ground, what is the maximum distance the ball will travel?

  1. 45 meters

  2. 50 meters

  3. 55 meters

  4. 60 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum distance the ball will travel can be calculated using the formula: d = (v^2 * sin(2 * theta)) / g, where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: d = (30^2 * sin(2 * 30)) / 9.81 = 55 meters.

Multiple choice

In a basketball game, a player shoots a free throw from a distance of 15 feet from the basket. If the basket is 10 feet high, what is the angle at which the player should shoot the ball to make the shot?

  1. 30 degrees

  2. 45 degrees

  3. 60 degrees

  4. 75 degrees
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The angle at which the player should shoot the ball to make the shot can be calculated using the formula: theta = arctan(h / d), where h is the height of the basket and d is the distance from the basket. Plugging in the values, we get: theta = arctan(10 / 15) = 45 degrees.

Multiple choice

A tennis player serves a ball with an initial velocity of 120 km/h. If the ball is hit at a height of 2 meters above the ground, what is the maximum height reached by the ball?

  1. 10 meters

  2. 15 meters

  3. 20 meters

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

The maximum height reached by the ball can be calculated using the formula: h = (v^2 * sin^2(theta)) / (2 * g), where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Since the ball is hit horizontally, the angle of projection is 0 degrees. Plugging in the values, we get: h = (120^2 * sin^2(0)) / (2 * 9.81) = 20 meters.

Multiple choice

A golfer hits a ball with a club, giving it an initial velocity of 60 m/s at an angle of 45 degrees to the horizontal. If the ball is hit at a height of 1 meter above the ground, what is the maximum distance the ball will travel?

  1. 120 meters

  2. 150 meters

  3. 180 meters

  4. 210 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum distance the ball will travel can be calculated using the formula: d = (v^2 * sin(2 * theta)) / g, where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: d = (60^2 * sin(2 * 45)) / 9.81 = 180 meters.

Multiple choice

A soccer player kicks a ball with an initial velocity of 25 m/s at an angle of 60 degrees to the horizontal. What is the maximum height reached by the ball?

  1. 12.5 meters

  2. 15 meters

  3. 17.5 meters

  4. 20 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum height reached by the ball can be calculated using the formula: h = (v^2 * sin^2(theta)) / (2 * g), where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: h = (25^2 * sin^2(60)) / (2 * 9.81) = 17.5 meters.

Multiple choice

A baseball player hits a ball with a bat, giving it an initial velocity of 35 m/s at an angle of 45 degrees to the horizontal. If the ball is hit at a height of 1.5 meters above the ground, what is the maximum distance the ball will travel?

  1. 52.5 meters

  2. 60 meters

  3. 67.5 meters

  4. 75 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum distance the ball will travel can be calculated using the formula: d = (v^2 * sin(2 * theta)) / g, where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: d = (35^2 * sin(2 * 45)) / 9.81 = 67.5 meters.

Multiple choice

In a basketball game, a player shoots a free throw from a distance of 18 feet from the basket. If the basket is 10 feet high, what is the angle at which the player should shoot the ball to make the shot?

  1. 35 degrees

  2. 40 degrees

  3. 45 degrees

  4. 50 degrees
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The angle at which the player should shoot the ball to make the shot can be calculated using the formula: theta = arctan(h / d), where h is the height of the basket and d is the distance from the basket. Plugging in the values, we get: theta = arctan(10 / 18) = 45 degrees.

Multiple choice

A tennis player serves a ball with an initial velocity of 130 km/h. If the ball is hit at a height of 2.5 meters above the ground, what is the maximum height reached by the ball?

  1. 12.5 meters

  2. 15 meters

  3. 17.5 meters

  4. 20 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum height reached by the ball can be calculated using the formula: h = (v^2 * sin^2(theta)) / (2 * g), where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Since the ball is hit horizontally, the angle of projection is 0 degrees. Plugging in the values, we get: h = (130^2 * sin^2(0)) / (2 * 9.81) = 17.5 meters.

Multiple choice

A golfer hits a ball with a club, giving it an initial velocity of 70 m/s at an angle of 30 degrees to the horizontal. If the ball is hit at a height of 1 meter above the ground, what is the maximum distance the ball will travel?

  1. 140 meters

  2. 160 meters

  3. 180 meters

  4. 200 meters
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The maximum distance the ball will travel can be calculated using the formula: d = (v^2 * sin(2 * theta)) / g, where v is the initial velocity, theta is the angle of projection, and g is the acceleration due to gravity. Plugging in the values, we get: d = (70^2 * sin(2 * 30)) / 9.81 = 180 meters.