Chapter 7, Problem 5RAT

When no air resistance acts on a fast-moving baseball, its acceleration is

(a) downward, g.

(b) due to a combination of constant horizontal motion and accelerated downward motion.

(c) opposite to the force of gravity.

(d) zero.

To determine

The correct option for the statement "When no air resistance acts on a fast-moving baseball, its acceleration is".

Answer to Problem 5RAT

The correct option for the statement "When no air resistance acts on a fast-moving baseball, its acceleration is" is option (a).

Explanation of Solution

A fast-moving baseball is similar to the motion of a projectile projected with a particular velocity. Hence, the baseball follows the path of a parabola as in projectile motion. The parabolic path of the baseball is due to the combination of horizontal as well as vertical components of motion. The horizontal component of velocity is constant since there is no horizontal acceleration. The vertical component of velocity changes because of the acceleration due to gravity acting downwards. Thus, the acceleration of the baseball is only due to the acceleration due to gravity acting vertically downwards.

The horizontal motion is a constant and therefore, it does not contribute to the acceleration of the baseball. The acceleration due to gravity always acts downwards. The force of gravity on any object moving under acceleration due to gravity also acts in the same direction. Since, the baseball will fall down at the end of the motion, there is some acceleration acting on it.

Conclusion:

Therefore, the correct option for the statement "When no air resistance acts on a fast-moving baseball, its acceleration is" is option (a).