Friction on a Surface

Friction on a surface.

Aim: To establish the relation between weight of a rectangular wooden block lying on a horizontal table and the minimum force required to just move it using a spring balance

Materials required: A rectangular block of wood with a hook , set of weights, strong thread and a spring balance.

Theory: The force of friction acting on a block of wood is proportional to the normal reaction acting on the block. By the third law of motion, normal reaction is equal to the weight of the object. So friction will depend on the weight of the object.

Procedure.: Measure the weight of the wooden block using the spring balance. Place the wooden block on the table. Attach one end of the thread on the hook and the other end on the spring balance. Slowly pull the wooden block holding the spring balance, gradually increasing the force. Record the reading on the spring balance when the block just starts moving Record your values in the tabular column. Repeat the experiment by increasing the weight of the block by placing extra weights on the wooden block. Plot a graph of net weight of the block against the minimum force required to move it.

Result ; The minimum force required to move the block was found to be directly proportional to the weight of the block.

Precautions;
1. The surface should be free of dust and Greece.
2. Thread should be inextensible.
3. Make sure that the thread is strong enough to withstand the force.
4.Take the reading exactly when the block starts moving

Spring Balance
Wooden Block

Table

Range of spring balance:…………………

Least count of spring balance:…………..

Zero error of spring balance:……………..

Weight of the wooden block:……………..

S.No | Weight added (N) | Net weight (N) | Reading of spring balance(N) | 1 | | | | 2 | | | | 3 | | | | 4 | | | | 5 | | | |