Question

Starting from rest, a 4.30-kg block slides 1.80 m down a rough 30.0° incline. The coefficient of kinetic friction between the block and the incline is ?k = 0.436.

(a) Determine the work done by the force of gravity. J

(b) Determine the work done by the friction force between block and incline. J

(c) Determine the work done by the normal force. J

(d) Qualitatively, how would the answers change if a shorter ramp at a steeper angle were used to span the same vertical height?

Answer 1

here,

mass , m = 4.3 kg

s = 1.8 m

theta = 30 degree

uk = 0.436

a)

the work done by the force of gravity, Wg = m * g* s* sin(theta)

Wg = 4.3 * 9.81 * 1.8 * sin(30) J

Wg = 38 J

b)

the work done by the friction force between block and incline, Wf = - uk * m * g * cos(theta) * s

Wf = - 0.436 * 4.3 * 9.81 * cos(30) * 1.8 J

Wf = - 28.7 J

c)

the work done by the normal force, Wn = N * s * cos(90)

Wn = 0 J

d)

when the height remians the same

the work done by the force of gravity, Wg = 38 J

the work done by the friction force between block and incline is increase as the block has to travel more distance

the work done by the normal remains remains the same zero