Hello, this is the last question that I can't seem to or be able to solve:

1. Jenny (75 kg) goes on a ski trip. She goes down a slope that's inclined at 15*. The drag coefficient of Jenny is 0.300, the surface of contact with air is 0.750 m^2 and the air density is 1,31 kg/m^3. The coefficient of kinetic friction between the skis and the snow is of 0,185.

Jennys speed according to her distance:

from 0 to 15m/s: between 0m and 50m
from 15 to 20 m/s: between 50m and 100m
constant 20m/s: 100m to 450m
from 20m/s to 0: 450m to 500m

Questions:

a) What is the Work done by the force of air resistance?

b) What is the Work done by the friction force between the skis and the snow?

c) What is the work of gravity?

d) What is the Power dissipated by the force of air resistance? What is the Power dissipated by the force of friction between the skis and the snow?

Thank you

To answer these questions, we need to apply the relevant physics formulas and concepts. Let's break down each question and explain the steps to find the answers.

a) What is the Work done by the force of air resistance?

Work is defined as the force applied over a distance. In this case, the force of air resistance can be calculated using the formula:

F_air = (1/2) * Cd * A * ρ * v^2

where F_air is the force of air resistance, Cd is the drag coefficient, A is the surface area of contact with air, ρ is the air density, and v is the velocity of the object.

To calculate the work done by the force of air resistance, we need to integrate the force over the distance traveled:

Work_air = ∫ F_air * dx

You mentioned that Jenny's speed changes over different distance intervals, so we need to calculate the work done in each interval separately.

b) What is the Work done by the friction force between the skis and the snow?

The work done by the friction force can be calculated using the formula:

Work_friction = μ * m * g * d

where μ is the coefficient of kinetic friction, m is Jenny's mass, g is the acceleration due to gravity (9.8 m/s^2), and d is the distance traveled.

Since you provided the distances for different speed intervals, we will calculate the work done by friction for each interval separately.

c) What is the work of gravity?

If there are no changes in height, the work done by gravity is zero since the force of gravity acts perpendicular to the direction of displacement.

d) What is the Power dissipated by the force of air resistance? What is the power dissipated by the force of friction between the skis and the snow?

Power is defined as the rate at which work is done. It can be calculated using the formula:

Power = Work / time

Since you have the values for work done in each interval (a and b), you can divide it by the corresponding time interval to find the power dissipated by air resistance and friction.

Remember to convert units to ensure consistency and accuracy in your calculations.

I hope this explanation helps you solve the problem. Good luck!