Q. A stone dropped from a window reaches the ground in 0.5 seconds -
i) calculate its speed just before it reaches the ground?
ii) what is its average speed during 0.5 sec?
iii) calculate the height of window from the ground?
Here,
Initial speed, u = 0
Acceleration, a = 9.8 m/s2
Time, t = 0.5 s
(i)
Using, v = u + at
=> v = 0 + (9.8)(0.5)
=> v = 4.9 m/s
This is the speed when the stone reaches the ground.
(ii)
Distance traveled, s = ut + ½ at2
=> s = 0 + ½ (9.8)(0.5)2
=> s = 1.225 m
So, average speed = 1.225/0.5 = 2.45 m/s
(iii)
Height of window from the ground is 1.225 m