One more quick convervation of energy problem

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SUMMARY

The skier's problem involves calculating the height of a slope using energy conservation principles. The initial speed is 5 m/s and the final speed at the bottom is 13 m/s. The correct formula to determine the height is derived from the conservation of mechanical energy, specifically using the equation h = (vi² - vf²) / (2g). The correct height calculation yields 7.3 meters, contrasting with the incorrect attempt of 14.9 meters due to misapplication of mass in the equation.

PREREQUISITES
  • Understanding of potential energy (PE) and kinetic energy (KE) concepts
  • Familiarity with the conservation of mechanical energy principle
  • Basic algebra for manipulating equations
  • Knowledge of gravitational acceleration (g = 9.81 m/s²)
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  • Review the conservation of mechanical energy in physics
  • Practice problems involving potential and kinetic energy calculations
  • Learn how to derive height from speed using kinematic equations
  • Explore the implications of mass in energy equations
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Students studying physics, particularly those focusing on mechanics and energy conservation principles, as well as educators looking for examples of energy problems in real-world scenarios.

crimsonn
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Homework Statement



A skier leaves a slope with an initial speed of 5 m/s. Her speed at the bottom of the slope is 13 m/s. What is the height of the slope?

Homework Equations


PE= mgh
KE= 1/2mv^2


The Attempt at a Solution



PE + KE1 = KE2

PE=KE2-KE1

mgh = 1/2mv^2 -1/2mv^2

gh = 1/2v^2 -1/2v^2

h = 1/2mv^2 -1/2mv^2 / g

when I plug everything in, I get 14.9

the answer is 7.3


what am I doing wrong?
 
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crimsonn said:
h = 1/2mv^2 -1/2mv^2 / g
Where have these masses appeared from? If these masses are just a typo and you really used,

h = (vi2 - vf2)/(2g)

Then you have simply plugged the numbers in wrong.
 

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