Question

1. Salim has a paper route. He puts his papers on a toboggan to pull them through the snow. The combined mass of the papers and the toboggan is 24kg. The coefficient of static friction between the toboggagn and the snow is 0.18. The coeefficient of kinetic friction between the toboggan and the snow is 0.10

a)with how much force must Salim pull in order to get the toboggan ro start moving?

b) how much force is needed to keep the toboggan moving at a constant speed?

2. When a car is accelerating, it will move in the direction of the net force. However, objects do not always move in the direction of the net force. Explain how this would be the case for a car coming to a stop at a traffic light? How would the diagram look with forces acting on the vehicle?

Answer 1

I think you can do #1.

#2)
F = m a
If your force is positive, your acceleration is positive. (negative mass does not occur in this subject)
HOWEVER
That says NOTHING about the magnitude or direction of VELOCITY.
If the car is headed North and puts the brakes on, the force will be South.
However until the speed reaches zero, the velocity remains North.

Answer 2

Find Fn by doing: Fn = mg, then, to find the minimum force required to start moving it, use Fk = Fn*Us ... (Us being static Friction).

To find the amount needed to keep it at a constant velocity,
use: Fs = Fn*Uk.

In your case, it would be:
Fk = 235.2*0.18 = 42.3N, to get it moving
Fs = 235.2*0.10 = 23.52, to keep it at a constant velocity.