Question

A ball falls vertically after being dropped.

The ball falls a distance dmetres in a time of t seconds.
dis directly proportional to the square of t.
The ball fals 20 metres in a time of 2 seconds.
(a) Find a formula for din terms of t.

Answer 1

d = 5t^2

Explanation:

"d is directly proportional to the square of t"

d = kt^2

To find k use

"The ball falls 20 metres in a time of 2 seconds."

20 = k(2^2)

20 = k(4)

Divide both sides by 4

5 = k

Using k = 5 the formula becomes

d = 5t^2