SOLUTION: "A 15 kg toboggan is pulled along the snow at a constant speed by a horizontal force of 22 N. How much more force is needed to pull the toboggan if two passengers, one with a m

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Question 1079993: "A 15 kg toboggan is pulled along the snow at a constant speed by a horizontal force of 22 N.
How much more force is needed to pull the toboggan if two passengers, one with a mass of 40 kg and the other with a mass of 65 kg are riding on it."

This was a two part question. In part one I had to find the coefficient of kinetic friction between the toboggan and the snow. That was straight forward: using the proper formula it came out to a coefficient of 0.15. Coefficient = Ff/FN = 22N/147N = 0.15

On part two do I add only the new masses together then use Ff = Mg x coefficient kinetic friction?

If so I'm looking at
Ff = 105 kg x 9.80 m/s^2 x 0.15 = 154.35 N or 132.35 N more than the original

Or is the question asking me to consider the new mass with the old mass?

Ff = 120 kg x 9.80 m/s^2 x 0.15 = 176.4 N which is 154.4 N more than the original
Answer by ikleyn(52835) About Me  (Show Source):
You can put this solution on YOUR website!
.
The normal force produced by 15 kg mass is m*g = 15*9.81 = 147.15 N (newtons)

The kinetic friction coef. = 22%2F147.15 = 0.15.   CORRECT !!


In the next step (in the Part 2) you need to use the mass of 15 kg + 40 kg + 65 kg.