Possible website title: Understanding GPE and KE Equations for Physics Homework

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The discussion focuses on understanding gravitational potential energy (GPE) and kinetic energy (KE) equations in physics homework. Participants calculate GPE for a 2 kg block and a 4 kg stone, with some confusion about the formulas for GPE at the highest point. There are questions about the simplicity of GPE calculations and the need for clarification on KE equations. The conversation highlights a lack of understanding regarding the relationship between mass, height, and energy calculations, particularly for kinetic energy. Overall, the thread emphasizes the need for clearer explanations of the relevant physics equations.
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Homework Statement


1) What is the GPE of a 2 kg block 5 meters above the floor?

2) Joe throws a 4 kg stone straight up and it reaches a height of 5 meters. What is its GPE at its highest point?

3) How high do you have to lift a 1 kg ball to give it 49 J of GPE?[/B]

4) What is the KE of a 4kg mass at 3 m/s?

5) What is the mass of an object that has 100J of KE when moving at 5 m/s?

Homework Equations


Honestly, the only thing I understand is the GPE stuff, which I believe is to simply multiply the mass and height together. I'm not sure if KPE is just as simple.

The Attempt at a Solution


1) 10J

2) I got 20J but it says "highest point" so I don't know if that requires a different formula.

3) Seems simple enough, I got 49 meters by dividing 49J by 1 kg.

4 and 5 and basically Kinetic energy in general is what I need help on.
 
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Sonny18n said:
1) 10J
Please quote a standard equation for this (answer is wrong).
Sonny18n said:
2) I got 20J but it says "highest point" so I don't know if that requires a different formula.
Why would the GPE at the highest point follow a different law from the GPE at any other point?
Sonny18n said:
4 and 5 and basically Kinetic energy in general is what I need help on.
You haven't been taught any equations for KE?
 
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