Work done on block by spring and friction

In summary, the problem asks for the work done by the spring and friction as a block moves from point A to point B along path 2, with given values for mass, force constant, and coefficient of kinetic friction. The equations for calculating work are provided, and the attempt at a solution involves plugging in the values and adjusting for a possible error in signs.
  • #1
JennV
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0

Homework Statement



In the system shown in the figure, suppose the block has a mass of 2.7 kg, the spring has a force constant of 480 N/m, and the coefficient of kinetic friction between the block and the floor is 0.18.

Find the work done on the block by the spring and by friction as the block is moved from point A to point B along path 2.

Diagram:
http://img706.imageshack.us/img706/5935/walker4ech08pr006.jpg

Homework Equations



Wspring = 1/2kx^2
Wfriction = -uk*m*g*x

The Attempt at a Solution



Wspring = 1/2(480)(0.020)^2 = 0.096
Wfriction = -(0.18)(2.7)(9.81)(0.020) = -0.0953532

I inserted these values into the system, but it said that my sign for Wspring is wrong, so I switched it to a negative. It stopped saying anything about my signs, but it won't say that it is correct. I'm not sure what is wrong...
THANKS.
 
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  • #2
Although the work done by the spring only depends on the initial and final positions, the work done by friction depends on the entire path taken---i.e. what's the distance during which friction does work?
 

Related to Work done on block by spring and friction

1. What is the formula for work done on a block by a spring?

The formula for work done on a block by a spring is W = (1/2)kx^2, where k is the spring constant and x is the displacement of the block from its equilibrium position.

2. How is the work done on a block by a spring related to its potential energy?

The work done on a block by a spring is equal to the change in potential energy of the block-spring system. This means that as the spring is compressed or stretched, work is done on the block and its potential energy increases or decreases accordingly.

3. How does friction affect the work done on a block by a spring?

Friction between the block and the surface it is on can reduce the amount of work done on the block by the spring. This is because some of the energy is converted into heat due to the frictional force, rather than being transferred to the block as work.

4. Can the work done on a block by a spring be negative?

Yes, the work done on a block by a spring can be negative if the spring is compressed and the displacement of the block is in the opposite direction of the force applied by the spring. This means that the potential energy of the block-spring system decreases and work is done by the system rather than on it.

5. How does changing the spring constant affect the work done on a block by a spring?

A higher spring constant will result in a greater amount of work being done on the block, as the spring is able to exert a stronger force. Conversely, a lower spring constant will result in less work being done on the block.

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