The problem of a rock thrown vertically up

A rock is thrown vertically upward from the ground with an initial speed 15m/s.

a. how high does it go
b. how much time is required for the rock to reach its maximum height?
c. what is the rock’s height at t=2.00s?

(Posted by Merhawi)

Answer:

(a)

u=15m/s

a=-10m/s²

v=0 m/s (at the max height)

S=?

v²-u²=2aS

S=v²-u²/2a

=225/20

=11.25 m

(b) From the above case

using v=u+at

t=v-u/a=1.5s

(c) Use S = ut + 1/2 at²

put t=2s, u = 15m/s, a=-10m/s²

S=30 – 20 = 10 m

 

(If you use g = 9.8 m/s² The answers will be slightly different)