Question

# A ball falls off a table and reaches the ground in 1s. Assuming g=10ms−2. Calculate its speed on reaching the ground and the height of the table.

A
5ms1 and 5m
B
20ms1 and 10m
C
10ms1 and 5m
D
30ms1 and 15m

Solution

## The correct option is C 10ms−1 and 5mGiven, Time taken, t=1s Initial velocity, u=0 Acceleration due to gravity, g=−10ms−2 (Upward direction is taken as positive) Let the final speed be v. From equation of motion,  v=u+gt v=(0−10×1) ms−1 v=−10ms−1 Minus indicates velocity in downwards direction. Let the height of table be h. Then displacement will be −h as the final position is below the initial position. From equation of motion,  −h=ut+12gt2 −h=0×1−12×(−10)×12 h=5 m

Suggest corrections