Practice MCQ Questions and answers on Physics-GK

When a bullet is fired from a gun, the gun exerts a force on the bullet in the forward direction. This is force is called as the action force. The bullet also exerts an equal and opposite force on the gun in the backward direction. Therefore a gun recoils when a bullet is fired from it.

The inability of a body to change its state of rest or its uniform motion in a straight line is called as Inertia.

Moment of inertia depends on distribution of body, axis of rotation and mass of the body. It is not dependent on angular velocity of the body.

An athlete runs before long jump to get advantage on inertia of motion.

The Moon's surface gravity is about 1/6th as powerful or about 1.6 meters per second. The Moon's surface gravity is weaker because it is far less massive than Earth. A body's surface gravity is proportional to its mass, but inversely proportional to the square of its radius.

A flick is given to the card with finger, the card flies away and the coin falls in the tumbler. It is explained by saying that due to inertia, the coin remained at its own place and the card went away due to the flick.

According to the second law of motion for a given force, the acceleration of the object is inversely proportional to the mass of the object. Therefore, more the mass less is the acceleration and vice versa.

In technical terms, the recoil is a result of conservation of momentum, as according to Newton's third law the force required to accelerate something will evoke an equal but opposite reactional force, which means the forward momentum gained by the projectile and exhaust gases will be mathematically balanced.