If the momentum of a body increases by 0.01%, its kinetic energy will increase by
Correct Answer :
0.02 %
Solution :
The correct option is 0.02 %.
Step 1: Establish the relationship between kinetic energy and momentum
The kinetic energy (K) of a body of mass m moving with velocity v is expressed as:
The momentum (p) of the body is defined as:
Rearranging the momentum formula to solve for velocity gives:
Substituting this velocity term into the kinetic energy formula yields:
Step 2: Relate small percentage changes using differentiation
Since the percentage change in momentum is extremely small (0.01%, which is far less than 10%), we can use the differential approximation method to find the corresponding change in kinetic energy.
Taking the natural logarithm () on both sides of the kinetic energy relation:
Applying logarithmic identities, this becomes:
Differentiating both sides with respect to their variables (noting that mass m is constant, so differentiates to zero):
Step 3: Compute the percentage increase in kinetic energy
Multiplying both sides of the differential relationship by 100 converts the fractional changes into percentage changes:
We are given that the percentage increase in momentum is 0.01%:
Substituting this value into the percentage relation:
Thus, the kinetic energy of the body increases by 0.02%.
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