Question

A ball is dropped from the top of 80 m high tower. If after 2 s of fall the gravity (g = 10 m/s2 ) disappears, then time taken to reach ground since the gravity disappeared is

Answer 1

Check the attachment

Answer 2

Answer:3sec

Explanation:

Distance from ground to B

s=ut +1/2at^2

=0×2+1/2×10×2^2

=20m

v^2-u^2=2as

v^2-0^2=2×10×20

v^2=40

v=20m

Therefore, remaining distance from point AtoB when gravity disappears is

80-20=60m

Therefore, time= remaining distance/speed

=60/20=3sec