Question

A grocery cart with mass of 11 kg is being pushed at constant speed up a flat 17 ∘ ramp by a force FP which acts at an angle of 17 ∘ below the horizontal.

(A) Find the work done by each of the forces (mg⃗ ,F⃗ N,F⃗ P) on the cart if the ramp is 17 m long.

Express your answer using two significant figures.

W_mg =

(B)

Express your answer using two significant figures.

W_N =

(C)

Express your answer using two significant figures.

WP =

Answer 1

A. The work done by gravity is against the direction of motion, and
gravity work = 11kg * -9.8m/s² * 17m * sin17 = -536.35 J
in two significant digits Wmg=-540 J
(B). FN is perpendicular to the direction of motion, so the work done by it is 0 J.
(C). The downslope component of the cart's weight is
W' = mgsinΘ = 11kg * 9.8m/s² * sin17º = 31.55 N,
so this must be the component of the applied force along the incline.
Then work = 31.55N * 17m = 536.35 J
to two significant digits

Wp=540 J

Answers in two significant figures

(A) -540 J. (B) 0 J . (C) 540 J