Mechanics (1d - Kinematics) - Quiz, Flashcards & Trivia

1. A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball when caught would be

Less than the speed it had when thrown upwards.

More than the speed it had when thrown upwards.

The same as the speed it had when thrown upwards.

In the absence of air resistance, the only force acting on the ball is gravity. When the ball is thrown upwards, it slows down due to the gravitational pull until it reaches its highest point where its velocity becomes zero. As the ball falls back down, it accelerates due to gravity, gaining speed. At the moment it is caught, the ball would have the same speed as it had when thrown upwards because the acceleration due to gravity is constant and the ball would have traveled the same distance upwards and downwards. Therefore, the correct answer is that the speed of the ball when caught would be the same as the speed it had when thrown upwards.

Explanation

In the absence of air resistance, the only force acting on the ball is gravity. When the ball is thrown upwards, it slows down due to the gravitational pull until it reaches its highest point where its velocity becomes zero. As the ball falls back down, it accelerates due to gravity, gaining speed. At the moment it is caught, the ball would have the same speed as it had when thrown upwards because the acceleration due to gravity is constant and the ball would have traveled the same distance upwards and downwards. Therefore, the correct answer is that the speed of the ball when caught would be the same as the speed it had when thrown upwards.

2. Suppose an object is in free fall. Each second the object falls

The same distance as in the second before.

A larger distance as in the second before.

With the same instantaneous speed.

With the same average speed

None of the above

When an object is in free fall, it accelerates due to gravity. This means that its velocity increases with each passing second. As a result, the object covers a larger distance in the second that follows compared to the second before. Therefore, the correct answer is that the object falls a larger distance as in the second before.

Explanation

When an object is in free fall, it accelerates due to gravity. This means that its velocity increases with each passing second. As a result, the object covers a larger distance in the second that follows compared to the second before. Therefore, the correct answer is that the object falls a larger distance as in the second before.

3. A free falling object is dropped from a height from rest. After falling for 1 second, the speed is about

5m/s

10m/s

100m/s

None of the above

When a free falling object is dropped from rest, it accelerates due to gravity. The acceleration due to gravity is approximately 9.8 m/s^2. After falling for 1 second, the object would have reached a velocity of approximately 9.8 m/s. However, due to air resistance, the actual speed may be slightly less than this. Therefore, the closest option is 10m/s.

Explanation

When a free falling object is dropped from rest, it accelerates due to gravity. The acceleration due to gravity is approximately 9.8 m/s^2. After falling for 1 second, the object would have reached a velocity of approximately 9.8 m/s. However, due to air resistance, the actual speed may be slightly less than this. Therefore, the closest option is 10m/s.

4. As an object falls freely in vacuum, its

Velocity increases.

Acceleration increases

Both velocity and acceleration increase.

Only distance increases.

When an object falls freely in a vacuum, there is no air resistance acting upon it. This means that the only force acting on the object is gravity. According to the laws of physics, when an object is subject to a constant force, it experiences a constant acceleration. In this case, the force of gravity causes the object to accelerate downwards. As the object accelerates, its velocity increases. Therefore, the correct answer is that the velocity of the object increases as it falls freely in a vacuum.

Explanation

When an object falls freely in a vacuum, there is no air resistance acting upon it. This means that the only force acting on the object is gravity. According to the laws of physics, when an object is subject to a constant force, it experiences a constant acceleration. In this case, the force of gravity causes the object to accelerate downwards. As the object accelerates, its velocity increases. Therefore, the correct answer is that the velocity of the object increases as it falls freely in a vacuum.

5. At the highest point of flight of a ball thrown upwards,

The acceleration is zero.

The acceleration is the minimal.

The acceleration is directed downward.

The acceleration is directed upward.

At the highest point of flight, the ball has reached its maximum height and is momentarily at rest before it starts to fall back down. At this point, the velocity of the ball is zero, but the acceleration is directed downward due to the force of gravity acting on it. This downward acceleration is responsible for bringing the ball back down to the ground.

Explanation

At the highest point of flight, the ball has reached its maximum height and is momentarily at rest before it starts to fall back down. At this point, the velocity of the ball is zero, but the acceleration is directed downward due to the force of gravity acting on it. This downward acceleration is responsible for bringing the ball back down to the ground.