To push a 9-kg crate up a frictionless Incline angled at 50° to the horizontal,

Question

To push a 9-kg crate up a frictionless Incline angled at 50° to the horizontal, a worker exerts a force of 160 N parallel to the incline. The crate moves a distance of 7 m What work is done on the crate by the worker? Submit Answer Tries 0/3 What work is done on the crate by gravity? Submit Answer Tries 0/3 What is the work done on the crat? due to the normal force of the inclined plane surface? Submit Answer Tries 0/3 What is the net work done on the crate Submit Answer Tries 0/3 If the crate begins at rest, what is the final speed of the crate as it is moved from the bottom to the top of the inclined plane? m/s Submit Answer Tries 0/3

Explanation / Answer

here,

mass of crate , m = 9 kg

theta = 50 degree

F = 160 N

s = 7 m

a)

the work done on crate by worker , Ww = F.s

Ww = 1120 J

b)

the work done on the crate by gravity , Wg = - m * g * s * sin(theta)

Wg = - 9 * 9.81 * 7 * sin(50) J

Wg = - 473.4 J

c)

the work done on the crate due to normal force , Wn = N * s * cos(90) = 0 J

d)

the net work done , W = Ww + Wg + Wn

W = 1120 - 473.4 J

W = 646.6 J

e)

let the final speed be v

using work energy theorm

work done = change in kinetic energy

646.6 = 0.5 * m * ( v^2 - 0)

646.6 = 0.5 * 9 * v^2

solving for v

v =12 m/s

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