Answer :

Mass of the block, m = 200 g = 0.2 kg

Acceleration due to gravity, g = 10 m/s2

Length of the incline plane, L = 10 m

Height of the incline plane, h = 3.2 m

(a.) Required work for lifting the block to the top of the incline = mgh

= 0.2×10×3.2

= 6.4 J

(b.) Work done against friction = 0 J (as the surface is frictionless)

Required work for sliding the block up = Work done against gravity

= 6.4 J

(c.) Let the speed of the block when it falls off the incline be v m/s.

The speed of the block when it is at rest on the top, u = 0 m/s

According to equation of motion, v2 - u2 = 2gh

v2 - 0 = 2×10×3.2

v2 = 64

v = 8 m/s

(d.) When the block slides down, let the speed of the block be v m/s

Change in kinetic energy of the block = work done by gravity + work done by friction

1/2 mv2 = mgh + 0

v2 = 2gh

v2 = 2×10×3.2 = 64

v = 8 m/s

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