Question

If someone is riding in the back of a pickup truck and throws a softball straight backward, is it possible for the ball to fall straight down as viewed by a person standing at the side of the road? Under what condition would this occur? How would the motion of the ball appear to the person who threw it?

Short answer

The person is riding at the back of a pickup truck and throws the softball straight in the backward direction with the same speed as the truck relative to the ground. Yes, it is possible that the person on the side of the road will see the ball fall straight down.

Step-by-step solution

Step 1: Frame of reference

A frame of reference is a collection of coordinates used to indicate the relationship between a moving observer and an event. The frame of reference is further classified into the inertial and non-inertial frames of reference.

Determine speed of truck

The person on the side of the road will see the ball fall straight down, as the person is at rest and has a different frame of reference.

This would happen as the person on the truck will see the ball moving downwards with a speed equal to the speed of the truck moving forward relative to the ground.