Question

Why does it happen?
A. A ship dips to a larger depth in fresh water as compared to marine water.
B. Fruits can easily be cut with a sharp knife.
C. The wall of a dam is broad at its base.
D. If a stationary bus suddenly speeds up, passengers are thrown in the backward direction.

Answer 1

A. The density of marine water is more than the fresh water due to which the buoyant force on the ship in marine water is more than the fresh water. Hence, the ship dips to a larger depth in fresh water as compared to marine water.

B. Since the sharp edged knife makes lesser contact with the fruits to be cut, thus the pressure exerted by it on the fruit is very large. Because of this large pressure, fruits are easily cut with a sharp knife.

C. We know pressure of liquid increases with depth. So, the wall of a dam is made broader at its base so that it is able to withstand the heavy pressure exerted by the river water.

D. If a stationary bus suddenly speeds up, passengers are thrown in the backward direction. This is because initially the whole body of a passenger inside the bus was in the state of rest. But, when the bus suddenly starts or speeds up, the lower half of the passenger's body comes in motion in the forward direction but the upper half still remains at rest due to inertia of rest. Hence, the passengers are thrown backward when a stationary bus suddenly speeds up.