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.