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

An iron ball and a wooden ball fall simultaneously from a height h. If the viscosity of the air is negligible, which ball will hit the ground first?

  1. Iron ball

  2. Wooden ball

  3. Both will hit the ground at the same time

  4. It depends on some other factors also
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In the absence of air resistance (negligible viscosity), all objects fall with the same acceleration due to gravity regardless of their mass. This is a consequence of Galileo's principle and Newton's second law: a = F/m = mg/m = g. Both balls will hit the ground simultaneously when dropped from the same height.

Multiple choice

Which of the following is not an example of a free fall?

  1. A boy throws a ball down from a window.

  2. Mango after ripening falls from the tree.

  3. A small bird falls down when a vulture pushes it until it touches the ground.

  4. A stone thrown up, stops at a certain height and then falls down.

  5. A baby falls from the terrace.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer as the bird is being pushed down by the vulture. It is not falling freely under the influence of gravitational force.

Multiple choice

Choose the correct option

  1. When a body falls freely, its initial velocity is zero.

  2. When a body is thrown vertically upwards, its final velocity is zero.

  3. When a body is thrown vertically upwards, its final velocity is equal to initial velocity.

  4. Both (1) and (2).

  5. 1, 2 and 3 are correct.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Both options, 1 and 2 are correct. So, the correct answer of this question is option 3

Multiple choice

Take a one-rupee coin and a piece of paper of same size as the coin. Drop both of them on the ground. You will notice that the coin will fall on the ground quickly but the paper will take time and float in air for some time. Why?

  1. Because paper is heavier than the coin.

  2. Because coin is heavier than paper and it will be pulled by the gravity with more attraction.

  3. Because air will help the flow of paper but resist the flow of coin.

  4. Because coin is pulled by earth's gravitation whereas gravitation has no effect on paper.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Because coin is heavier than paper and it will be pulled by the gravity with more attraction

Multiple choice

A body is thrown horizontally with a velocity √2gh from the top of a tower of height h. It strikes the level ground through the foot of the tower at a distance x from the tower. The value of x is

  1. h

  2. h/√2

  3. 2h

  4. √2h/√3

  5. h/√3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Initial vertical component = 0 m.s-1 Distance to be traveled = -h Applying the second equation of motion, -h = 1/2(-g)(t2) t = √(2h/g) Horizontal component of velocity = √2gh Distance = velocity* Time x = √2gh*√(2h/g) = 2h (Correct Answer)

Multiple choice

A ball is dropped from the top of the building. The ball takes 0.5 seconds to fall past the 3 m length of a window some distance from the top of the building. If the velocities of the ball at the top and at the bottom of the window are Vt and Vb respectively, then Vt + Vb = ? (Take g = 10 m.s-2). (Round off the answer to the nearest integer)

  1. 10 m.s-1

  2. 14 m.s-1

  3. 17 m.s-1

  4. 12 m.s-1

  5. 11 m.s-1
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the total height till bottom of the window be x m. Then, the height from the top of the building to the top of the window = (x - 3) m . Let time taken by the ball to reach from top of the building to the top of the window = t s, then the time taken to reach the bottom of the window from the top of the building is (t + 0.5) s. Applying the equation, (x - 3) = 5*t2 x = 5 (t + 0.5)2 Solving, we get t = 0.35 seconds x = 3.6125 m Applying the third equation of motion u = 0 m.s-1 Vt2 - u2 = 2*g*0.6125 Solving we get Vt = 3.5 m.s-1 Now again applying the third equation of motion, Vb2 - u2 = 2*g*3.6125 Solving we get Vb = 8.5 m.s-1 Adding the two Vt + Vb = 12 m.s-1 (Correct Answer)

Multiple choice

You are given two identical plastic balls, which you can drop from various floors of a building to carry out your experiment. If a ball doesn't break after being dropped, it may be reused without suffering any loss of quality. But if both balls break before you have reached the highest floor, then the experiment is a failure. What is the least number of times you must drop the balls in order to reach the highest floor?

  1. 12

  2. 14

  3. 25

  4. 50

  5. 60
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The answer is 14. You drop the first plastic ball from the 14th floor. If it breaks, then you can determine the highest floor by dropping the plastic ball no more than 13 times (drop it from the 1st floor, and if it doesn't break, drop it from the 2nd floor, and if it still doesn't break, drop from the 3rd, etc). If the first ball survives the drop from the 14th floor, you then drop it from the 27th floor (14 + 13 = 27). If it breaks, you can complete your test in no more than 12 drops with the second ball by dropping it between the floors 15 to 26. If from the 27th floor, the first ball still doesn't break, the next floor to drop it from is the 39th (14 + 13 + 12 = 39). If it breaks, drop the second ball from floors 28 to 38 (max 11 drops). Repeat the experiment the same way whenever the first ball doesn't break; after the 39th floor should be the 50th floor (14 + 13 + 12 + 11), then the 60th floor (14 + 13 + 12 + 11 + 10), and so on. If the first ball survives 11 drops, you will be on the 99th floor. In that case, it only takes one more drop to complete the whole test.

Multiple choice

A parachute descends slowly whereas a stone dropped from the same height falls rapidly, because ________.

  1. stone is heavier then parachute

  2. special mechanisms are present in parachute

  3. a parachute has a larger surface area and air resistance is more

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A parachute descends slowly due to its large surface area, which creates significant air resistance (drag force). The stone falls rapidly because it has small surface area relative to its mass, so air resistance is minimal compared to gravitational force. Air resistance is proportional to surface area and velocity.