Power Needed to Pull Skier Up Slope

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SUMMARY

The discussion centers on calculating the power required for a motor to pull a skier of mass 78.7 kg up a 31.9° slope at a constant speed of 1.04 m/s, considering a coefficient of kinetic friction of 0.270. The key equations involved are P = F * V for power, and the forces acting on the skier include gravitational force components and friction. The net force is zero due to constant velocity, leading to the equation T = F|| - Ff, where T is tension, F|| is the parallel component of gravitational force, and Ff is the force of friction. The correct approach requires calculating the normal force as mg cos(x) to determine the frictional force accurately.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with trigonometric functions in physics
  • Knowledge of frictional forces and their calculations
  • Ability to apply the power formula P = F * V
NEXT STEPS
  • Calculate the normal force on an inclined plane using mg cos(x)
  • Determine the force of friction using the formula Ff = μ * Normal Force
  • Explore the relationship between tension, gravitational forces, and friction on inclined planes
  • Practice similar problems involving power calculations in physics
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This discussion is beneficial for physics students, educators, and anyone interested in understanding the dynamics of forces on inclined planes, particularly in the context of real-world applications like skiing and motorized towing systems.

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Homework Statement


A skier of mass 78.7 kg is pulled by a motor-driven cable up a 31.9 ° slope at a constant speed of 1.04 m/s. If the coefficient of kinetic friction between the skis and the slope is 0.270, what power must be delivered by the motor pulling the cable?

Homework Equations



P=FV

The Attempt at a Solution


The Fnet of the skier will be 0 because the velocity is constant.
To find the F|| of the skier I used the equation mgsin(x) and umg to find Force friction(Ff)
Therefore, T=F||-Ff
and therefore P=T*v
but everytime I do this I get the wrong answer, and I don't know why??Please help!
 
Last edited:
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To find the force of friction, you need the normal force, which is balancing w_perpendicular (mg cos x). Force of friction is mu times this normal force.

And also, are w_parallel and friction in the same direction as each other, or opposite? Is just one of these forces or both of them pointing opposite of tension?
 

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