Question

The speed at which a ball bits the ground is proportional to the

height to which the ball rebounds. If the ball hits the ground at
a speed of 20 miles per hour and rebounds to a height of 10 feet,
then how fast must it be traveling (in miles per hour) to rebound
to a height of 15 feet?

Answer 1

30 mph

Explanation:

let s represent speed and h represent rebound.

Given that s is proportional to h then the equation relating them is

s = kh ← k is the constant of proportion

To find k use the condition s = 20, h = 10, then

20 = 10k ( divide both sides by 10 )

2 = k

s = 2h ← equation of proportionality

When h = 15 , then

s = 2 × 15 = 30 mph