Question

If an object is thrown straight up and air resistance is negligible, then its speed when it returns to the starting point is the same as when it was released. If air resistance were not negligible, how would its speed upon return compare with its initial speed? How would the maximum height to which it rises be affected?

a) Speed would be greater; maximum height would be lower.

b) Speed would be greater; maximum height would be higher.

c) Speed would be the same; maximum height would be lower.

d) Speed would be the same; maximum height would be higher.

Answer 1

Air resistance causes the speed upon return to be lower than the initial speed due to energy dissipation and results in a lower maximum height reached by the object.

Step-by-step explanation:

Considering the effect of air resistance on the motion of an object thrown straight up, we can say with certainty that air resistance would cause the object's speed upon return to be lower than its initial speed. Without air resistance, the object would return to its starting point with the same speed it had when thrown, because energy is conserved in the ideal case of a system where gravity is the only force acting on the object.

However, with the presence of air resistance, there's a dissipative force working against the object's motion, which does two things: it reduces the object's upward speed, leading to a lower maximum height; and it continues to oppose its motion as it falls back down, which reduces its speed upon return. Therefore, because of air resistance, there would be less kinetic energy at the initial point when the object returns.

The correct option for this scenario, where we consider the effects of air resistance on the motion of a projectile, is (a) Speed would be greater; maximum height would be lower.