Work Power Energy Test

Result

Work Power Energy Test - 3

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Question 1
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Statement I A block of mass m starts moving on a rough horizontal surface with a velocity v. It stops due to friction between the block and the surface after moving through a certain distance. The surface is now tilted to an angle of 30° with the horizontal and the same block is made to go up on the surface with the same initial velocity v. The decrease in the mechanical energy in the second situation is smaller than that in the first situation.

Statement II The coefficient of friction between the block and the surface decreases with the increase in the angle of inclination.

A
Statement I is true, Statement II is true; Statement II is the correct explanation for Statement I

B
Statement I is true, Statement II is true;

C
Statement II is not a correct explanation for Statement I

D
Statement I is true; Statement II is false

Solution

In statement-I

Decrease in mechanical energy in case I

ΔU₁ = 1/2 mv²

But decrease in mechanical energy in case II will be

ΔU₂ = 1/2 mv² - mgh

ΔU₂<ΔU₁

or statement I is correct.

Statement IIis false, as the coefficient of friction is independent of the angle of inclination.