A falling stone accelerates at a constant rate of 10 m/s square. It is dropped from rest down a deep well, and 3 s later a splash is heard as it hits the water below.

Question

a) How fast will it be moving as it hits the water?
b) What will be its average speed over the three seconds?
c) How deep is the well?
d) What have you assumed about the speed of sound?

Answer 1

(c) if the speed of sound is m m/s, then if the depth of the well is h m,
It takes t seconds to hit the water, where 5t^2 = h, so it takes t=√(h/5) seconds to hit the water
Then, adding up the times,
h/m + t = 3
(d) speed of sound is constant
(a) v = 0-10t = -10√(h/5)
(b) h/t
This gives the avg speed while falling
ignoring the time spent in the water

Answer 2

calculated

Answer 3

Student

Answer 4

good

Answer 5

a b c d