Inclined force problem

In summary, the conversation is about finding the force required to push a 22kg bobsled on a track with a coefficient of kinetic friction of .10 down a 6.0 degree incline and achieve a speed of 60km/h at the end of 75m. The person discussing the problem shares their calculation process, including finding the acceleration of the sled, normal force, and force of friction. Another person points out that the horizontal component of force of gravity was missed in the calculation and suggests setting up an equation for the net force. The original person clarifies their misunderstanding and thanks the other person for their help. Lastly, someone else asks for an explanation on finding the force of friction, to which the first person responds
  • #1
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Hi it's been a while since I posted here so I will avoid the latex on this question and hope you understand.

The coefficient of kinetic friction for a 22kg bobsled on a track is .10. What force is required to push it down a 6.0 degree incilne and achieve a speed of 60km/h at the end of 75m?

So this is what I did:

I found the acceleration of the sled to be 1.85 m/s^2
Then I found the normal force= mg times cos 6= 214N
I then found the force of friction to be 21N
I then set Net Force equal to ma= 22 times 1.85 which equaled 40.7
Then I set 40.7 equal to forcex minus force of friction
and solved for forcex

Can anyone point out what I did wrong?
Thanks
 
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  • #2
What forces acting on the sled parallel to the track?
 
  • #3
You mean like force of friction and Sin (6) times mg which is the horizontal component of Force of gravity
 
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  • #4
ace123 said:
Sin (6) times mg
That's the one you missed. (Three forces act, including the applied force which you are trying to find.)

So set up an equation for the net force.

ace123 said:
You mean like force of friction and Sin (6) times mg which is the horizontal component of Force of gravity
Yes.
 
  • #5
O I was confused by that. So wouldn't then net force just equal the applied force?
 
  • #6
ace123 said:
So wouldn't then net force just equal the applied force?
Why would you say that? The net force is the sum of all the forces acting on the sled--the applied force is just one of those forces. (Pay attention to direction--sign--when you add the force components.)
 
  • #7
Well I figured the ohter forces cancel out since the object was at rest in the beginning and needed an applied force to move.
 
  • #8
No reason to assume so. Especially when you can calculate the forces and know for sure.
 
  • #9
Yea I forgot it could be moving but just not accelerating. Thanks for your help.
 
  • #10
We must assume (lacking information to the contrary) that it starts from rest. But that doesn't mean it was just sitting there waiting to be pushed.
 
  • #11
I'm solving the same problem. I don't understand how to find the friction force. Can someone explain in this particular problem?
 
  • #12
There is a formula for finding the force of friction. It's the coefficient of friction multiplied by the normal force. If you can find the normal force then I don't see your problem.
 

1. What is an inclined force problem?

An inclined force problem is a physics problem that involves calculating the forces acting on an object that is on an incline or slope. These types of problems often require using trigonometry and understanding concepts such as friction and gravity.

2. How do I approach solving an inclined force problem?

The first step in solving an inclined force problem is to draw a free-body diagram, which shows all the forces acting on the object. Then, you can use trigonometry to break down the forces into their components and use Newton's laws of motion to analyze the forces acting on the object.

3. What are the common forces involved in an inclined force problem?

The most common forces involved in an inclined force problem are the weight or gravitational force, the normal force, and the force of friction. Other forces, such as applied forces or tension, may also be present depending on the specific problem.

4. How does the angle of the incline affect the forces in an inclined force problem?

The angle of the incline can affect the forces in an inclined force problem in several ways. For example, a steeper incline will result in a greater component of the weight force acting down the slope, which can increase the force of friction. Additionally, the angle can affect the trigonometric calculations used to determine the forces' components.

5. Are there any tips for solving inclined force problems?

Some tips for solving inclined force problems include carefully drawing a free-body diagram, labeling all the forces and their components, and double-checking your calculations. It can also be helpful to practice solving different types of inclined force problems to become familiar with the process and common pitfalls.

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