(a) Net work done on the book is 8.66 J
(b) Speed at the end of the displacement is 2.40 m/s.
(a) Work done is defined as the product of force and displacement.
Mathematically Work done (W) = F.s
F = force applied on the object = 20N
s = displacement travelled by the object due to force applied = 0.5m
When the object is placed at an angle (A)
W = F * d * cos(A)
where, A = angle of ramp = 30°
Therefore, work done is:
W = 20 * 0.5 * cos30
W = 8.66 J
(b) Speed is the rate of change of distance with respect to time.
Also, Work done is equal to change in Kinetic energy.
Since the initial kinetic energy is zero:
W = KE(final)
W = (1/2) * m * v²
where v = final velocity
m = mass of the book = 3 kg
=> 8.66 =(1/2) * 3 * v²
v² = 5.773
v = 2.40 m/s
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