Overcoming friction and then some.

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In summary, the conversation discussed calculating the distance, work, and kinetic energy involved in pushing a loaded wheelbarrow with a mass of 130 kg and a horizontal force of 120 N. The frictional force of 85 N was also taken into account. The final results showed that the wheelbarrow traveled 0.94 m, 112.8J of work was done on the wheelbarrow, 79.9J of work was done by the frictional force, and the final kinetic energy of the wheelbarrow was 109.85J. The conversation also clarified the concept of NET force and its role in the calculations.
  • #1
anyone1979
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[SOLVED] Overcoming friction and then some.

Can anybody help me figure if I have this right?

You push a loaded wheelbarrow of mass 130 kg, exerting a horizontal force of 120 N as you do so. As the wheelbarrow moves, the frictional force acting on it is 85 N.
(a) If you begin from rest, how far do you push the wheelbarrow before reaching a moderate walking speed of 1.3 m/s?
(b) Over this distance, how much work do you do on the wheelbarrow?
(c) How much work does the frictional force do on the wheelbarrow?
(d) What is the final kinetic energy of the wheelbarrow?


a) a = 120/130 = .9m/s^2
1.3^2 = 2(.9)(x)
1.69/1.8 = .94 m

b) W = 120(.94) = 112.8J

c) W = 85(.94)(-1) = -79.9J

d) K = 1/2(130)(1.3^2) = 109.85J
 
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  • #2
anyone1979 said:
Can anybody help me figure if I have this right?

You push a loaded wheelbarrow of mass 130 kg, exerting a horizontal force of 120 N as you do so. As the wheelbarrow moves, the frictional force acting on it is 85 N.
(a) If you begin from rest, how far do you push the wheelbarrow before reaching a moderate walking speed of 1.3 m/s?
(b) Over this distance, how much work do you do on the wheelbarrow?
(c) How much work does the frictional force do on the wheelbarrow?
(d) What is the final kinetic energy of the wheelbarrow?


a) a = 120/130 = .9m/s^2
1.3^2 = 2(.9)(x)
1.69/1.8 = .94 m

b) W = 120(.94) = 112.8J

c) W = 85(.94)(-1) = -79.9J

d) K = 1/2(130)(1.3^2) = 109.85J
In calculating the acceleration, you must use the NET force acting on the wheelbarrow, not just the applied force.
 
  • #3
But isn't the NET force equal to the force (120) since that is the only force without a nonzero x-component?

or am I wrong?
 
  • #4
anyone1979 said:
But isn't the NET force equal to the force (120) since that is the only force without a nonzero x-component?

or am I wrong?
What about the given friction force which opposes the motion in the horizontal direction?
 
  • #5
You are right, thank you.

Will this cover it? (NET force = applied force - friction force)
 
  • #6
anyone1979 said:
You are right, thank you.

Will this cover it? (NET force = applied force - friction force)
yes, that is correct, in the x direction.
 
  • #7
Thank you for your help
 

Related to Overcoming friction and then some.

1. How does friction affect motion?

Friction is a force that opposes the motion of an object. It acts in the opposite direction to the direction of motion and can reduce the speed of an object or bring it to a stop.

2. What are some ways to reduce friction?

One way to reduce friction is by using lubricants, such as oil or grease, to create a slippery surface for objects to slide against. Another way is by using smoother materials, such as ball bearings, to reduce the contact surface area between two objects.

3. Can friction ever be beneficial?

Yes, friction can be beneficial in certain situations. For example, it helps us walk without slipping and provides the necessary grip for car tires to move on the road. It also helps us write with a pen or pencil by creating enough friction for the ink to stick to the paper.

4. How can we overcome friction to increase speed?

In order to overcome friction and increase speed, we can reduce the contact surface area between two objects, use a lubricant to create a slippery surface, or apply a force in the direction of motion to counteract the force of friction.

5. Is there a limit to how much friction can be reduced?

Yes, there is a limit to how much friction can be reduced. This is because all surfaces have microscopic imperfections that create friction, and it is impossible to completely eliminate these imperfections. However, we can reduce friction to a great extent by using techniques such as lubrication and using smoother materials.

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