Question Details

Which one of the following pairs of quantities has the same dimension ?

Options

A

force and work done

B

momentum and impulse

C

pressure and force

D

surface tension and stress

Correct Answer :

momentum and impulse

Solution :

The correct option is momentum and impulse.

To find which pair of physical quantities has the same dimensions, we can derive the dimensional formula for each quantity step-by-step.

1. Momentum and Impulse:
Linear momentum is defined as the product of mass and velocity:

Momentum=Mass×Velocity

The dimensional formula for mass is [M] and for velocity is [LT-1]. Thus, the dimensional formula for momentum is:

[Momentum]=[MLT-1]

Impulse is defined as the product of force and the time interval for which it acts:

Impulse=Force×Time

The dimensional formula for force is [MLT-2] and for time is [T]. Thus, the dimensional formula for impulse is:

[Impulse]=[MLT-2]×[T]=[MLT-1]

Since both momentum and impulse share the same dimensional formula [MLT-1], they have the same dimensions.

Let us verify the other options to show why they do not match:

2. Force and Work done:

[Force]=[MLT-2]

Work done is the product of force and displacement:

[Work done]=[MLT-2]×[L]=[ML2T-2]

These two have different dimensions.

3. Pressure and Force:
Pressure is defined as force per unit area:

[Pressure]=[MLT-2][L2]=[ML-1T-2]

Since Force has dimensions [MLT-2], their dimensions are different.

4. Surface tension and Stress:
Surface tension is defined as force per unit length:

[Surface tension]=[MLT-2][L]=[MT-2]

Stress is defined as force per unit area:

[Stress]=[MLT-2][L2]=[ML-1T-2]

These two also have different dimensions.

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