How the 2m height affect with this one

Question

The ball is thrown from a height of 2m at an initial speed of 15m/s and the starting direction forms a 35 degree angle.

a) what is the ball flight time when it hits the ground?
b) maximum height?
c) air travel time?

Answer 1

(a)

 

Height as a function of time is

 

h(t) = -4.9t² + (15sin35°)t + 2,

 

with t in seconds and h in meters.

 

Set h(t) = 0 and solve the resulting quadratic equation for t, which you should know how to do.  You will get a negative and a positive solution.  Since time starts at t=0, keep only the positive solution.

 

(b)

 

h_max occurs at the vertex of the height-vs.-time parabola, which is at 

 

t = -(15sin35°)/[2(-4.9)] sec = ? sec

 

Evaluate h(t) at this value of t and get h_max in meters.

 

(c)

 

This is the same as the t calculated in part (a).