How much work was done aginst friction?

In summary, the problem involves a 75 N block being pushed up a ramp to a platform 2.0 m high. The coefficient of friction is 0.300 and the ramp is 6.0 m long. The questions asked include the amount of work done, work done against friction, work done against gravity, and the power developed. The solution involves using trigonometry to find the angle and then using the equations for work and power to solve for each question. The work done is 135J, the work done against gravity is mgh J, and the work done against friction is the difference between the total work and the work against gravity. The power developed is found using the equation P=FV, where F is the
  • #1
xc630
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0
Hello I am having toruble solving this problem. I would appreciate any help.

A 75 N block is pushed at 5.0 m/s up a ramp 6.0 m long to a platform 2.0 m high. If the coefficient of friction is 0.300
a) how much work was done?
b) how much work was done aginst friction?
c) how much work was done against gravity?
d) how much power was developed?

I solved for theta using trig and got 19 degrees.
Then I solved for work with the equation [Fw(sintheta+ucostheta)]h and got 91J.
I am confused on how to solve for the work against friction and the work aginst gravity though.
Thanks for any help
 
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  • #2
ok here is the way to proceed

first draw the free body diagram for it

you will get the following things from it
1) weight mg(75 N) acting downwards
2) then normal reaction mgcos(teta)
3) the force 0.3*R(normal reaction)

now solve for it using
w=f*s
where f is the force required to move up
where s is the distance moved , use trignometry and u will get it
the work according to me is 135J

c)then for the work done against gravity,to reach the topest point u will need mgh J where h is 2 m in ur case

b)from the total work done subtract this and u will get the work done against friction

d) use P=FV
where F is the force to move up and v is velocity given(5 m/s)

hope this helped u. please tell me If i am wrong.
-benzun
 
  • #3
note keep the trigrometic values in fraction itself don't find the angle
 

1. How is work calculated against friction?

Work against friction is calculated by multiplying the force required to overcome friction by the distance over which the force was applied. This is known as the work-energy theorem.

2. What is the role of friction in work?

Friction is a force that opposes motion, and therefore it requires work to overcome it. The amount of work done against friction depends on the coefficient of friction, the normal force, and the distance over which the force is applied.

3. How does the coefficient of friction affect the amount of work done against friction?

The coefficient of friction is a measure of the roughness between two surfaces. The higher the coefficient of friction, the more work is required to overcome friction. This is because a higher coefficient of friction means there is more resistance to motion.

4. Can work against friction be negative?

Yes, work against friction can be negative. This occurs when the force applied to overcome friction is in the opposite direction of the motion. In this case, the work done against friction is actually work done by friction, and it acts to slow down the object.

5. How does the normal force affect the work done against friction?

The normal force is the force exerted by a surface on an object in contact with it. The normal force affects the work done against friction because it determines the amount of force required to overcome friction. The greater the normal force, the more work is required to overcome friction.

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