Question

Vanessa throws a tennis ball in the air. The function h(t) = -15t2 + 45t + 10 represents the distance in feet, that the ball is from the ground at any time in seconds, t. What is the maximum height of the ball?

Answer 1

43.75feet

Explanation:

Given the height of the tennis ball expressed as;

h(t) = -15t^2 + 45t + 10

At maximum height, the velocity of the ball is zero

v = dh/dt

dh/dt = -30t + 45

Since dh/dt = 0, hence;

0 = -30t + 45

30t = 45

t = 45/30

t = 3/2

t = 1.5secs

Substitute t = 1.5 into the expression given

h(1.5) = -15(1.5)^2 + 45(1.5) + 10

h(1.5) = -15(2.25)+67.5+10

h(1.5) = -33.75+77.5

h(1.5) = 43.75feet

Hence the maximum height of the ball is 43.75feet