Work Energy And Power Question 150

Question: A particle is released from the top of two inclined rough surfaces of height ’ h ’ each. The angle of inclination of the two planes are 30 and 60 respectively. All other factors (e.g. coefficient of friction, mass of block etc.) are same in both the cases. Let K1 and K2 be the kinetic energies of the particle at the bottom of the plane in two cases. Then

Options:

A) K1=K2

B) K1>K2

C) K1<K2

D) data insufficient

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Answer:

Correct Answer: C

Solution:

[c] Work done in friction is W=(μmgcosθ)s

=(μmgcosθ)(hsinθ)=μmghcotθ

Now cotθ1=cot30=3

And cotθ2=cot60=13

W1>W2 i.e., kinetic energy in first case will be less. (K=mghW) Or K1<K2



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