Question

A brass ball is hanging from a stiff cotton thread. Draw a neat labelled diagram showing the forces acting on the brass ball and the cotton thread.

Answer 1

Weight is the force due to gravity. The thread that supports the load must exert an upward force that must be equal to the weight of that object. This force is called the normal force. The brass ball will experience a pull due to cotton thread. This force is the Tension in the cotton thread.

Formula Used:
The weight acting on an object is given by:
$W = Mg$
where, $W$ is the weight, $M$ is the mass and $g$ is acceleration due to gravity.

Complete answer:
Gravitational force is the fundamental force that acts on everybody having mass and that is under the influence of gravity. The weight of an object is the force due to gravity. Let $M$be the mass of a brass ball. Then, its weight $W$ is given by
$W = Mg$

Brass is an alloy and is composed of copper and zinc. Therefore, the ball is supposed to be heavy. It should be tied with a strong rope. It is given that the brass ball is hanging from a stiff cotton thread. There must be a normal force acting downwards because the thread that supports the load must exert an upward force that must be equal to the weight of that object. The normal force is denoted by $N$.

There will also be a force that will be exerted due to cotton thread. This force is the Tension. . It is denoted by $T$. The direction of tension is so as to pull the brass ball. The tension acts upwards in the string and is equal to the weight of the supported mass. Greater the weight greater is the tension.

Note: The weight of any object is not to be confused with the mass of that object. Weight is due to the force of gravity and varies from place to place for the same body. For example, the weight of an object on Earth is not the same as that on the Moon. On the other hand, mass is the quantity that remains constant everywhere. It is assumed that the brass ball hanging from a stiff cotton thread is steady. It is not oscillation nor it is twisting the cotton thread. The cotton threads are not flexible and therefore they may break due to high tension.