Question

Calculate the friction of the person on ski. We use the situation from example 5.1 "Skiing Exercise" from the text book, but we change the slope to 15 degrees. Tips: - The gravity force of the person is 608 N. - You first have to calculate the perpendicular component of the gravity force. This is also the normal force.

Answer 1

Answer: Friction (Fk) = 46.2N.

Explanation: In the attachment, there is the drawing of the forces acting on the skiing person. As the person is in movement, the formula to calculate the friction is Fk = μk.N, where μk is the coefficient of kinetic friction and N is normal force. Normal force is the force necessary to keep a person "above" the ground. To find the normal force as suggested, we use the representation of the forces in the attachment. With it, it's shown that to calculate N:

cos 15° =
`(N)/(Fg)`

N = Fg·cos 15°

N = 608·(-0.76)

N = - 461.9N

Now, with N and knowing the coefficient, which can be found in Physics Text Books and it is 0.1, we have:

Fk = 0.1·(-461.9)

Fk = - 46.2N

The friction is negative because it is pointing to the opposite side of the reference.