Question

An object is dropped in an unknown planet from height 50 m, it reaches the ground in 2 s . The acceleration due to gravity in this unknown planet is
(a) g = 20 m s⁻²
(b) g = 25 m s⁻²
(c) g = 15 m s⁻²
(d) g = 30 m s⁻²

Answer 1

A ball is dropped in a unknown planet from height 50m .
∴ initial velocity of ball is zero.e.g., u = 0 m/s
distance covered by body to reach the surface of planet is 50m
e.g., h = 50m
Let Acceleration due to gravity on planet = a
time taken , t = 2 sec

Use formula, S = ut + 1/2 at²
Here, S = h = 50m , u = 0 and t = 2 sec
so, 50 = 1/2 × a × 2²
a =25 m/s²

Hence, option (b) is correct