In the following questions, each question contains Statement I(assertion) and StatementII(reason). Each questions has four choices a, b, c, and d out of which only one is correct.
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 titled 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 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 angel of inclination.

Options

A. (a) Statement I is true, Statement II is true, Statement II is a correct explanation for Statement I.
B. (b) Statement I is true, Statement II is true, Statement II is not a correct explanation for Statement I.
C. (c) Statement I is true, Statement II is false.
D. (d) Statement I is false, Statement II is true.

Answer

C

Explanation

Decrease in mechanical energy in case I will be
`DeltaU_1=1/2mv^2`
But decrease in mechanical energy in case II will be
`DeltaU_2=1/2mv^2-mgh`
`:. DeltaU_2ltDeltaU_1`
Hence, Statement 1 is correct. More ones, statement 2 is wiring.
Therefore, option (c) is correct.