Test: Uniform Circular Motion - ACT MCQ

When the body is at the highest point of its motion. This is because at the highest point the tension = centrifugal force – weight. This is the minimum value for tension throughout the motion.

When the string is horizontal, the tension in the string and the centrifugal force are opposite to each other. Centrifugal force can be calculated as mv²/r = 50 N. Hence the tension = centrifugal force = 50 N.

At the lowest point, the body experiences centrifugal force and the weight in the same direction, opposite to the direction of tension in the string. Centrifugal force can be calculated as mv²/r = 8 N. Hence the tension = weight + centrifugal force = 28 N.

Angular velocity is the rate of change of angular displacement. Here the angular velocity is 11 rad/s. This implies that in one second the stone rotates by an angle of 11 rad. Hence in 0.5 s it will cover an angular displacement if 5.5 rad.

The centrifugal force always acts away from the center of the circle in which the body is moving. In contrast to this, the centripetal force always acts towards the center of the circle, keeping the body moving in the circle.

Centripetal force is responsible for keeping bodies moving in circular motion. The centripetal force is directly proportional to the square of the tangential velocity and inversely to the radius of circle.

The centrifuge utilizes the centrifugal force produced during circular motion. Centrifuge is commonly used to separate platelets from blood samples. It is an important equipment for studying blood. Other variations of centrifuge include devices like cream separator etc.

At the highest point, the tension and the weight are in the same direction but the centrifugal force is in the opposite direction. Centrifugal force can be calculated as mv²/r = 50 N. Hence the tension = centrifugal force-weight = 30 N.

A body moving in vertical circular motion experiences these four forces – centripetal force, centrifugal force, force of gravity, and resistance offered by the medium in which it is moving. Apart from these, it does not experience any other force in normal conditions.

Angular velocity = Tangential velocity/Radius. When we put in the values and calculate the angular velocities for each of the circular motions, we see that both the angular velocities are equal to each other and the value is 4 rad/s.