Question

A ball is projected horizontally from the top of a building. One second later:

A. It goes upward
B. It accelerates
C. It falls vertically
D. It slows down

Answer 1

One second after being projected horizontally from the top of a building, a ball accelerates due to gravity. It retains its horizontal velocity while its vertical velocity increases. The correct answer is C.

Step-by-step explanation:

One second after a ball is projected horizontally from the top of a building, the correct statement about its motion is that it accelerates due to the force of gravity. The option that states the ball goes upward is incorrect because once the ball is in air, gravity pulls it downward. The ball does not fall vertically immediately as it has a horizontal component of motion. Additionally, the ball does not slow down; instead, its horizontal velocity remains constant (if we ignore air resistance) while the vertical velocity increases due to gravity.

In solving related problems on projectile motion, we need to use the physics concepts of free fall and projectile motion. These concepts help explain the ball's motion after being projected horizontally.

For instance, in the given reference where a ball is thrown horizontally from the top of a 60.0-m building:

1. The time the ball is in the air can be calculated using the formula for free fall under gravity, since the vertical motion is independent of the horizontal motion.
2. The initial horizontal component of the velocity can be determined by using the horizontal distance and the time of flight.
3. The vertical component of the velocity just before the ball hits the ground can be calculated using the formula v = u + at, where u is the initial velocity (which is zero in the vertical direction), a is the acceleration due to gravity, and t is the time the ball has been falling.
4. The total velocity (both horizontal and vertical components) just before the ball hits the ground can be found by combining the horizontal and vertical velocities vectorially.

To demonstrate that acceleration is independent of an object's velocity, such as in the experiment with ball A, ball B, and ball C, the student would need to measure the time it takes for each ball to reach the ground, ensuring that the only force acting on the balls during their fall is gravity.

The graph of the ball's horizontal velocity vs. time is a horizontal line, indicating constant velocity. The graph of the ball's vertical acceleration vs. time is a horizontal line below the time axis, indicating constant acceleration due to gravity, in the downward or negative direction.