The velocity of a body which hasfallen freely under gravity varies as gᵖhʷ ,where g is the acceleration due to gravity at the place and h is the height through which the body has fallen. Determine the values of p and w..
Correct Answer :
p=1/2 and q=1/2
Solution :
The correct option is p=1/2 and q=1/2 (where q corresponds to the exponent w of height h in the question statement).
To find the values of p and w (referred to as q in the options), we can use the method of dimensional analysis.
Let the velocity of the body be represented by . According to the problem statement, the velocity varies as . We can write this relation as an equation with a dimensionless constant :
Let us write down the dimensions of each physical quantity involved:
1. Dimensions of velocity (distance/time) are:
2. Dimensions of acceleration due to gravity (acceleration) are:
3. Dimensions of height (length) are:
4. The constant is a dimensionless quantity, so it has no dimensions.
Now, substituting the dimensions of all quantities into our equation:
Simplifying the right-hand side of the equation:
For the equation to be dimensionally correct, the exponents of the corresponding dimensions on both sides must be equal.
Equating the power of time on both sides:
Equating the power of length on both sides:
Substitute the value of into the equation:
By mapping the exponent from the question to in the options, we find:
and (since ).
Access expert-curated educational resources and study materials—completely free.
Create, conduct, and manage professional online assessments with Crey. Perfect for teachers and institutes.
Copyright © 2026 Crey. All Rights Reserved.