# To find the force constant of a helical spring by plotting a graph between load and extension - Physics Practical Class 11 Viva Questions with Answers.

1) What is a rigid body?

A body is said to be a rigid body when it doesn’t undergo any change in its length, volume or shape on the application of force.

2) What is a deforming force?

A balanced force that produces deformation in a body is known as the deforming force.

3) Define stress.

The restoring force exerted per unit area by the molecules of the deformed body is known as stress.

4) Give the unit of stress.

The unit of stress is newton per meter squared

$$\begin{array}{l}Nm^{-2}\end{array}$$
.

5) Define the yield point.

The yield point is a stage beyond the elastic limit, up to which there is no more extension, but the thinning of wire remains uniform.

6) Why do you remove kinks before starting the experiment?

7) What is meant by elasticity?

Elasticity is the property of a body that enables it to regain its normal shape after being stretched or compressed by a deforming force.

8) What is meant by elastic limit?

It is the upper limit of the stretching or compressing ability of a body. Beyond that limit, the body cannot regain its original shape. It will lose its elastic property and deform permanently.

9) What is a perfectly elastic body?

A perfectly elastic body regains its original shape completely and immediately after removing the deforming force.

10) Is quartz elastic or not?

Yes, quartz is highly elastic in nature.

11) What is a perfectly plastic body?

It does not regain its normal shape even after the removal of the deforming force.

12) What are a few examples of perfectly plastic bodies?

Putty, wax, paraffin, etc., are a few examples of perfectly plastic bodies.

13) What is stress?

Stress is the internal restoring force exerting per unit area of a deformed object.

14) What is the formula for stress?

The stress formula is Stress = Restoring force / Area.

15) What is meant by tensile stress?

If there occurs an increase in the given body’s length, then stress is known as tensile stress.

16) What is meant by compression stress?

If there occurs a decrease in the given body’s length, then stress is known as tensile stress.

17) What is meant by tangential stress?

If the deforming force is exerted tangentially, the resulting stress is known as tangential stress.

18) What is Hooke’s Law?

Within the threshold of elasticity, the object’s stress is proportional to its strain.

19) What is ductile material?

Ductile material is one that displays a large plastic range above the elastic limit.

20) What are a few examples of ductile materials?

Silver, copper, iron, aluminium, gold, etc., are a few examples of ductile materials.

21) What is brittle material?

A brittle material is one that displays a very short plastic range.

22) What are a few examples of brittle materials?

Cast iron, glass, ceramic, graphite, etc., are a few examples of brittle materials.

23) What is the measuring unit of strain?

There is no unit for strain.

24) Who was the first scientist to analyse the stretching of metals?

Robert Hooke

25) What is the difference between pressure and stress?

Pressure is the amount of force exerted per unit area. On the other hand, stress is the restoring force exerted per unit area.