Mechanical Energy Homework: Find E of 0.13 kg Ball at 5.00 m

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SUMMARY

The mechanical energy of a 0.13 kg ball moving at 20.0 m/s and positioned 5.00 m above the ground is calculated to be 32.4 J. This total energy includes both kinetic energy (Ek) and potential energy (Ep). The kinetic energy is computed using the formula Ek = 1/2mv², resulting in 26 J. The potential energy is derived from the formula Ep = mass x gravity x height, yielding 6.37 J. The sum of these energies confirms the total mechanical energy as 32.4 J.

PREREQUISITES
  • Understanding of kinetic energy calculations using Ek = 1/2mv²
  • Knowledge of potential energy calculations using Ep = mass x gravity x height
  • Familiarity with basic physics concepts such as mass, velocity, and gravitational force
  • Ability to perform unit conversions and basic arithmetic operations
NEXT STEPS
  • Study the principles of mechanical energy conservation in physics
  • Learn about the differences between kinetic and potential energy
  • Explore real-world applications of mechanical energy in engineering
  • Investigate the effects of varying mass and height on potential energy calculations
USEFUL FOR

Students studying physics, educators teaching mechanical energy concepts, and anyone interested in understanding energy calculations in motion.

cybernerd
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Homework Statement



A 0.13 kg ball moves at a rate of 20.0 m/s at the point where it is 5.00 m above the ground. How much mechanical energy does the ball have with respect to the ground?

Homework Equations



Ek = 1/2mv^2

The Attempt at a Solution



Ek = 1/2mv^2
Ek = 1/2(0.13kg)(20m/s)^2
E = 26 J

The assignment says my answer should be 32.4 J.
Obviously, I am doing something wrong, but I'm not sure how to incorporate the "with respect to the ground" bit into my equations.

Somebody offer me some guidance, please?
 
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I can't comment on WHY this is so.. but apparently.. the answer includes the potential energy of the ball as well

= mass x gravity x height

= .13 * 9.80 * 5m = 6.37J

26 J + 6.37J = 32.4J



Not really helping but I'm not familiar with mechanical energy...
 
Hmm...that is strange...I really don't like the way that the question is worded.

But that did help, thank you.
 

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