Question

"You throw a rock at 25m/s at an angle of 25.8511 degrees hitting a target 50m away on the ground in 2.22s." (this is on a flat surface)
Vi=25m/s
Theta=25.8511 degrees
x=50m
t=2.22s
and of course g=9.81m/(s^2)

"How high does the rock fly in the air?"


I know this problem should be a simple plug and solve but my answer does not match the one in the back of my book which is 6.05m. Test coming up and I want to know how to reach that answer or if the book is wrong, what the right answer is.

Please show steps and what equation to use.

Answer 1

my calculator is definitely in degrees

Answer 2

Vi = 25 sin 25.8 = 10.9 m/s up
v = Vi - 9.8 t
how long till v = 0?
9.8 t = 10.9
t = 1.11 seconds
how high?
h = ho + 10.9 (1.11) - 4.9 (1.11)^2
= ho + 12.1 - 6.04
= ho + 6.06

ho is because you rally did not throw the rock from ground level did you?
I did not bother to carry 3 sig figs, you may do so of course