Kinetic Friction and skis thrust

In summary, the problem involves Sam, who has a mass of 71.0 kg, skiing down a 51.0 m high slope at an 11.0 degree angle using jet-powered skis with a thrust of 210 N. His speed at the bottom is 41.0 m/s. The equations used are net force = ma and kinematic equations. The free body diagram shows the components of gravity, thrust, and friction forces. To find the normal force, the gravity force is calculated using the mass and acceleration due to gravity, and then multiplied by the cosine of the slope angle. The other component of gravity is calculated using the sine of the slope angle. The normal force is then added to the thrust force to
  • #1
BlakeGriffin
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Homework Statement


Sam, whose mass is 71.0 kg , takes off down a 51.0 m high, 11.0 degree slope on his jet-powered skis. The skis have a thrust of 210 N . Sam's speed at the bottom is 41.0 m/s .


Homework Equations


I'm not sure which equation(s) to use.
Net Force= ma and some kinematic equations maybe?


The Attempt at a Solution


This is the free body diagram that I came up with.
http://img291.imageshack.us/i/fbdy.jpg/ (It's not to scale)
There is also the thrust force coming from the skis in the opposite direction of the friction force. I couldn't fit them all in. Btw the dashed lines are the components of the gravity force.

If my free body diagram is right, then normal force = FG Cos(theta) which is one of the components of the gravity force. The other component of gravity is FG Sin(theta)

FG is mg = (71 KG)(9.8 m/s^2)=695.8 N
FN=FG Cos(theta)=695.8(cos(11))0=683N
The other component of FG is =FGSin(theta)=695.8(Sin(11))=133N

Since this component of gravity and the thrust force coming from the skis both point down the hill (or whatever) I get 133+210=343N pointing in that direction.

I don't know where to go from here.. Can anyone help me?
 
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  • #2
Ummm...what's the problem asking? Is it looking for the coefficient of friction or something?
 

FAQ: Kinetic Friction and skis thrust

1. How is kinetic friction related to skiing?

Kinetic friction is the force that resists the motion of two surfaces sliding against each other. In skiing, kinetic friction occurs when the skis slide across the snow. The amount of kinetic friction between the skis and the snow determines how quickly the skier can accelerate or decelerate.

2. What causes skis to have more or less thrust?

Thrust is the force that propels an object forward. In skiing, thrust is generated by the skier's movements and the shape of the skis. When the skier leans forward and shifts their weight to the front of the skis, this creates more thrust. Similarly, skis with a larger surface area and a curved shape can also generate more thrust.

3. How does the type of snow affect kinetic friction and thrust on skis?

The type of snow can greatly impact the amount of kinetic friction and thrust experienced by skis. For example, wet and slushy snow creates more friction, making it harder for skis to slide and reducing thrust. On the other hand, dry and powdery snow creates less friction, allowing skis to glide more easily and generating more thrust.

4. Does the weight of a skier affect kinetic friction and thrust?

Yes, the weight of a skier can affect the amount of kinetic friction and thrust experienced while skiing. A heavier skier will create more pressure on the skis, increasing the amount of friction between the skis and the snow. This can make it harder for the skier to move and generate thrust. On the other hand, a lighter skier may have less friction and an easier time generating thrust.

5. How does the angle of a slope affect kinetic friction and thrust?

The angle of a slope can also affect the amount of kinetic friction and thrust experienced while skiing. A steeper slope will increase the force of gravity, making it harder for skis to slide and reducing thrust. On a flatter slope, there is less resistance from gravity, allowing for easier movement and more thrust.

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