Calculating Work and Change in Thermal Energy

Therefore, in summary, we must use the equations W = F*d*cos(Θ) and ΔEth = FkΔr to calculate the work done by the person to pull the sled and the change in thermal energy experienced by the system. It is important to consider the coefficient of kinetic friction and the angle of the hill in order to accurately calculate the work done and the change in thermal energy.
  • #1
alyssad

Homework Statement


In the question, a person is pulling a 156 kg sled up a hill. A 620 N force is used to pull the sled up the hill that has an angle of 29° with the horizontal. The sled is pulled a distance of 26 m, and the kinetic friction coefficient is 0.0622. The system has been defined as the sled and the surface of the ground.

I need to calculate the amount of work the person is using to pull the sled, and I need to calculate the change in the thermal energy experienced by the system.

Homework Equations


W = F*d*cos(Θ)
ΔEth = FkΔr

The Attempt at a Solution


I've been trying to do W = μkmgΔr*cos(Θ), but I don't think I'm doing it correctly.

And I think I need to know the work to make finding the change in thermal energy easier.

Thank you!
 
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  • #2
alyssad said:

Homework Statement


In the question, a person is pulling a 156 kg sled up a hill. A 620 N force is used to pull the sled up the hill that has an angle of 29° with the horizontal. The sled is pulled a distance of 26 m, and the kinetic friction coefficient is 0.0622. The system has been defined as the sled and the surface of the ground.

I need to calculate the amount of work the person is using to pull the sled, and I need to calculate the change in the thermal energy experienced by the system.

Homework Equations


W = F*d*cos(Θ)
ΔEth = FkΔr

The Attempt at a Solution


I've been trying to do W = μkmgΔr*cos(Θ), but I don't think I'm doing it correctly.

And I think I need to know the work to make finding the change in thermal energy easier.

Thank you!
It looks as though you have only found the work done by the person to overcome friction.

What if the coefficient of friction were zero. If so, would it not be the case that the person would still have to do work?
 
  • #3
The change in thermal energy is equal to the frictional work, assuming that the system consists of the universe.
 

1. What is work in terms of thermal energy?

Work in terms of thermal energy is the transfer of energy that results in a change in temperature. This can occur through mechanical work, such as stirring a pot of soup, or through electrical work, such as running a heating element in a stove. Work can also be done on a system, such as compressing a gas in a piston, which can result in an increase in thermal energy.

2. How is work related to change in thermal energy?

Work and change in thermal energy are directly related. When work is done on a system, it can result in a change in thermal energy, either by adding or removing heat from the system. This is known as the first law of thermodynamics, which states that energy cannot be created or destroyed, only transferred or converted from one form to another.

3. What is the formula for calculating work?

The formula for calculating work is W = F x d, where W is work, F is the force applied to an object, and d is the distance over which the force is applied. In terms of thermal energy, this formula can be used to calculate the work done on a system, which can then be related to the change in thermal energy.

4. How is work measured in terms of thermal energy?

Work is measured in units of Joules (J) in terms of thermal energy. This is because Joules are the standard unit for measuring energy, and work is a form of energy transfer. Other units of work, such as calories or foot-pounds, can also be converted to Joules for consistency in calculations involving thermal energy.

5. What is the relationship between work and heat in terms of thermal energy?

There is a close relationship between work and heat in terms of thermal energy. Both are forms of energy transfer, and can result in a change in the temperature of a system. However, work is a transfer of energy through mechanical or electrical means, while heat is a transfer of energy through thermal contact. This distinction is important in understanding how work and heat contribute to changes in thermal energy.

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