A Stone is thrown upward with a speed of 15.m/sec from edge of cliff 85.m high?

Question

a)How much later does it reach the bottom of the cliff?
b)What is its speed just before hitting?
c)To what height will the stone rise from the edge of the cliff?
d)what total distance did it travel?

Answer 1

First assume that there is no effect from air resistance

Find the height above the cliff that the stone reaches

v.v - u.u = 2as
u = initial velocity
v = final velocity(at top) = 0
a = acc. due to grav = 9.8 m / s.s
s = distance travelled(need to find)

Rearranging, s = v.v / 2a
s = 15*15 /19.6
s = 11m

Add this to 85m = 96m. This is th height from top of travel to the floor

Now we have this we can answer part a):

Use s = ut + 0.5at.t
So s = 0.5t.t u = 0 (top of motion)
t = sqrt(2s)
t = sqrt(192)
t = 13.86s

b) v.v - u.u = 2as
u = 0 (top of motion)
v = sqrt(2*9.8*96)
v = 43.4 m/s

c) We did this part right at the beginning. Ans:11m

d) This is the easy part.
Total distance = 2*distance to top of motion + height of cliff
= 2*11 + 85
= 107 m

Answer 2

Need to tell us the effect of wind resistance.