Question

9.
A ball is dropped from the top of a tower of height
of 100 m and at the same time another ball is
projected vertically upwards from ground with a
velocity 25 m/s along the same vertical line. At
what height from the ground will the two balls
collide? (g = 10 m/s2)
(1) 20 m
(2) 32 m
(3) 40 m
(4) 55 m​

Answer 1

Explanation:

• givenH=100m u=25m/s h=1/2gt2 H-h=ut-1/2gt2 , H=ut , t=H/t , t=100/25=4seconds. H-h=25×4-1/2×10×4×4=100-80=20m