Gen question about work-energy principle

In summary, the correct formula for finding the total work done by the engine of a truck driving up a slope is: Work done = Gain in PE + Gain in KE + Work done against friction. The loss in KE should be considered negative in the formula, as it is converted into potential energy. This formula aligns with the concept of energy conversions and conservation.
  • #1
Boogeyman
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0
Hello, I am confused about this concept. Say, a truck drives up a slope. It decelerates as it ascends. I am required to find the total work done by the engine of the truck, and I know this to be:

Work done=Gain in PE + Loss in KE + Work done against friction

However I'm unsure whether the the loss in KE is negative or postive. Is it the magnitude I'm considering?
 
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  • #2
Hi Boogeyman!

Boogeyman said:
Hello, I am confused about this concept. Say, a truck drives up a slope. It decelerates as it ascends. I am required to find the total work done by the engine of the truck, and I know this to be:

Work done=Gain in PE + Loss in KE + Work done against friction

However I'm unsure whether the the loss in KE is negative or postive. Is it the magnitude I'm considering?

Your formula is off. It should read:

Work done=Gain in PE + Gain in KE + Work done against friction​

Since your losing KE it will come out negative in the formula.This should fit the intuitive sense of energy conversions and conservation of energy.
(Kinetic energy is converted to potential energy, canceling out in the work-done formula.)
 
  • #3
I like Serena said:
Hi Boogeyman!



Your formula is off. It should read:

Work done=Gain in PE + Gain in KE + Work done against friction​

Since your losing KE it will come out negative in the formula.


This should fit the intuitive sense of energy conversions and conservation of energy.
(Kinetic energy is converted to potential energy, canceling out in the work-done formula.)


Oh man thanks a bunch I have finals tomorrow and this was the only thing that was gray in my mind.
 

What is the work-energy principle?

The work-energy principle is a fundamental concept in physics that states that the work done on an object is equal to the change in its kinetic energy. In other words, the energy transferred to or from an object is equal to the change in its motion.

How is the work-energy principle used in scientific research?

The work-energy principle is used in many areas of scientific research, including mechanics, thermodynamics, and electromagnetism. It allows scientists to analyze and predict the motion and energy changes of various systems, from simple objects to complex systems.

What are some real-world applications of the work-energy principle?

The work-energy principle has many real-world applications, such as calculating the efficiency of machines, predicting the motion of objects in collisions, and understanding the behavior of energy in various systems. It is also used in fields like engineering, architecture, and design to optimize the performance of structures and devices.

Can the work-energy principle be violated?

No, the work-energy principle is a fundamental law of physics and cannot be violated. It is based on the conservation of energy, which states that energy cannot be created or destroyed, only transferred or transformed from one form to another.

What are some common misconceptions about the work-energy principle?

One common misconception is that work is only done when a force causes an object to move a certain distance. However, work is also done when a force acts on an object without causing it to move, such as holding a heavy object above the ground. Another misconception is that the work-energy principle only applies to mechanical systems, when in fact it applies to all forms of energy.

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