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Friction Problems: Need Help

  • Thread starter mmoran
  • Start date
  • #1
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Homework Statement


A sled of mass 13.4 kilograms is pulled along flat snow-covered ground. The static friction coefficient is 0.334, and the kinetic friction coefficient is 0.111.
I solved both part a and b, but im having trouble with part c.
c. Once moving, what force is needed to accelerate the sled 2.69 meters per second per second?



Homework Equations


am=f
u=f/n


The Attempt at a Solution



Im confused on how to do this.
So Its asking for the force pushing the sled forward. Using the formula am=f
if i plug in acceleration and the mass i get 13.4x2.69=36.046, but it said it was wrong.
Am I missing something? Do I need to factor in frictional force?
Would I add 14.6 to 36.046? 14.6 is the force needed to push the object at a constant velocity.
 

Answers and Replies

  • #2
Andrew Mason
Science Advisor
Homework Helper
7,560
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Homework Statement


A sled of mass 13.4 kilograms is pulled along flat snow-covered ground. The static friction coefficient is 0.334, and the kinetic friction coefficient is 0.111.
I solved both part a and b, but im having trouble with part c.
c. Once moving, what force is needed to accelerate the sled 2.69 meters per second per second?



Homework Equations


am=f
u=f/n


The Attempt at a Solution



Im confused on how to do this.
So Its asking for the force pushing the sled forward. Using the formula am=f
if i plug in acceleration and the mass i get 13.4x2.69=36.046, but it said it was wrong.
Am I missing something? Do I need to factor in frictional force?
Would I add 14.6 to 36.046? 14.6 is the force needed to push the object at a constant velocity.
Do a freebody diagram of the accelerating sleigh. What are the forces acting on the sleigh? What do they necessarily sum to?

AM
 

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