A block of mass m = 5.9 kg is pulled up a è = 21° incline as in the figure with a force of magnitude F = 34 N.

Question

(a) Find the acceleration of the block if the incline is frictionless.
1
Your response differs from the correct answer by more than 10%. Double check your calculations. m/s2

(b) Find the acceleration of the block if the coefficient of kinetic friction between the block and incline is 0.12.

Answer 1

Wb = mg = 5.9kg * 9.8N/kg = 57.82N. =
Weight of block.

Fb = (57.82N,21deg.) = Force of block.

Fp = 57.82sin21 = 20.72N. = Force parallel to the incline.

Fv = 57.82cos21 = 53.98N. = Force perpendicular to incline. = Tne Normal.

Fn = Fap-Fp = 34 - 20.72 = 13.28N. =
Net force. Fap = Force applied.

a. Fn = ma,
a = Fn/m = 13.28 / 5.9 = 2.25m/s^2.

b. Ff = u*Fv = 0.12 * 53.98 = 6.48N. =
Force of friction.

Fn = Fap - Fp -Ff = 34 - 20.72 - 6.48 =
6.8N.

a = 6.8 / 5.9 = 1.15m/s^2.