Problema Solution

A model rocket is launched with an initial upward velocity of 40 m/s. The Rockets hight h (in meters) after t seconds is given by the following.

H=40t-5t^2

Find all the values of t for which the rockets high is 15 meters

Answer provided by our tutors

We need to find t such that H(t) = 15, that is, we need to solve the quadratic equation:

40t-5t^2=15

........

click here to see the equation solved for t

........

t1 = 7.6 s

t2 = 0.4 s

The rocket will reach the height of 15 meters twice: first time 0.4 seconds after lunch and second time 7.6 seconds after lunch.