Working out kinetic energy and speed

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SUMMARY

The discussion focuses on the relationship between potential energy (PE) and kinetic energy (KE) in a frictionless system. It establishes that the maximum kinetic energy is equal to the maximum potential energy lost, confirming the principle of energy conservation. The participants clarify that while kinetic energy allows for the calculation of speed, velocity is a vector quantity that includes direction, which cannot be determined solely from KE. The exchange of energy between PE and KE is emphasized as a fundamental concept in mechanics.

PREREQUISITES
  • Understanding of potential energy (PE) and kinetic energy (KE)
  • Basic principles of energy conservation in physics
  • Familiarity with vector quantities and their properties
  • Knowledge of equations relating mass, kinetic energy, and velocity
NEXT STEPS
  • Study the conservation of mechanical energy in frictionless systems
  • Learn how to calculate kinetic energy using the formula KE = 0.5 * m * v²
  • Explore the differences between speed and velocity in physics
  • Investigate potential energy calculations with different reference points
USEFUL FOR

Students studying physics, educators teaching energy concepts, and anyone interested in understanding the principles of energy conservation and motion dynamics.

Meezus
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Homework Statement


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Homework Equations

The Attempt at a Solution


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a) I think I just have to work out the potential energy and the maximum kinetic energy would is the same?

c) Once I've found the kinetic energy, I'm able to work out velocity. Would the velocity be the maximum speed?

c) I think I can take the PE from A and the PE C and take them away from each other. With this number I'd have the KE of C which i'd work out velocity with?
 
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Your approach is correct. Thus problem is a simple matter of the exchange of energy between PE and KE.
 
To be accurate...
Meezus said:
the potential energy and the maximum kinetic energy would is the same?
Since there's no friction, the loss in PE equals the gain in KE. So the maximum loss in PE equals the maximum gain in KE.
PE is a relative thing. You cannot say exactly what the PE is at some point unless you have defined some reference value, such as the PE at another point.
Meezus said:
Once I've found the kinetic energy, I'm able to work out velocity. Would the velocity be the maximum speed?
No, velocity is a vector. Given the KE and the mass you can deduce the magnitude of the velocity (i.e. its speed) but not the direction.
 

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