Maximum velocity at the lowest point

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Homework Help Overview

The discussion revolves around a physics problem concerning a car on a frictionless surface descending a hill. Participants are exploring the relationship between potential energy (PE) and kinetic energy (KE) to understand why the maximum speed of the car occurs at the lowest point of the hill.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants are examining the conservation of energy principle, questioning how it relates to the maximum velocity at the lowest point. There are discussions about the relative values of potential energy at different heights and the implications of assuming no potential energy at the top of the hill.

Discussion Status

The conversation is active, with participants raising questions about the definitions and implications of potential and kinetic energy. Some have offered insights into the energy transformations occurring as the car descends, while others are clarifying concepts related to potential energy.

Contextual Notes

There are assumptions being made about the nature of potential energy, particularly regarding its value at the top of the hill. The discussion includes varying interpretations of energy conservation and the implications of height on potential energy.

helpinghand
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Say that there is a car on a top of the hill and it was on a frictionless surface, explain why the maximum speed of the car would occur at the lowest point of the hill?

In this case would you prove it through the conservstion of energy PE + KE = PE + KE?

If so, how does this prove that Vmax occurs at the lowest point?

Any help would be great, Thanks :)
 
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What can you say about PE at the top vs at the bottom? Which is higher?
 
Assume that there is no PE at the top of the hill...

What do you mean which is higher?
 
helpinghand said:
Assume that there is no PE at the top of the hill...

What do you mean which is higher?


PE is a relative phenomenon. U can't say that there is no PE at the top.
if there is no PE at the top...PE at the bottom should be negative
 
viplav said:
PE is a relative phenomenon. U can't say that there is no PE at the top.
if there is no PE at the top...PE at the bottom should be negative

Oops... typo, PE = mgh and KE = 0
 
hi friend

Assume that height of the hill is 'h' m.

now initially as the car is rest on the top of the hill...KE is zero and PE is 'mgh'

when the car is at the bottom of the hill the total PE at the top should be KE at the bottom...since PE at the bottom is zero

At any point in between top and bottom...the total energy is the sum of both PE and KE...but at the bottom the total energy is only KE so v is max at this point
 

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