Question

A team of dogs pulls a sled with a large box of food on it. The coefficient of kinetic friction between the sled and the snow is μ_ks.

a) Draw separate, carefully labeled free-body diagrams for the sled and for the box (assume the box is not strapped down, and that air resistance is negligible).

b) Suppose the sled has mass m_s and the box has mass m_b, and that the coefficient of kinetic friction between the box and the sled is μ_kb. Find an expression for the force from the dogs (F_dogs) needed to pull the sled at a constant speed with the box resting on top of it. Give your answer in terms of the given variables and, if necessary, g.

c) Later, a person standing behind the sled grabs the box and holds it still so that the sled slides out from under it while remaining in contact with the box. What is the F_dogs needed to pull the sled at a constant speed now?

Answer 1

for Food, Mb Uk for I sled, Merentes Nb fab \lo, fors M. a Non e Moga

fra frictional force between box and Bred. fre = forectional force between kled and ice. Ne = Normal dreaction on Bled by ice. Nb = Normal reaction on bon by sled. de force by dog. ta

If sled is moving with Constant Velocity #o nd box 15 not moving than eve Carides the is lateral force and bort aled acts - as a systlon Mb I Mbg + M₂ g ... fals: like the Melo For = fire for constant Velocity Id = Uks & (Mb + Me) (c) When box demains art di est by abblying force and bled moving with constant velocity from conden it then kinetic toictional force acts between sled and box.

Velocity. .. Fl- forn & tre for constant - Шк - Nь | Шк, 1 - Шкр. 9 4 кл. /M, M. Ja Па = || Прь Мь + Шк, (к), 4 м/] |
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