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Converted document POTENTIAL ENERGY EXAMPLES

POTENTIAL ENERGY EXAMPLES

EXAMPLE I
Find the gravitational potential energy of the castaway with respect to the oceans surface and the oceans floor. Assume that gravity pulls with a force of 10 m ⁄ s2
figure images/2.png
PE = mgΔh
PE = (50 kg)⎛⎝10(m)/(s2)⎞⎠(150 m − 50 m)
PE = 50, 000 ( kgm2)/(s2) = 50, 000 Joules
and
PE = mgh
PE = (50 kg)⎛⎝10(m)/(s2)⎞⎠(150 m − 0 m)
PE = 75, 000 (kgm2)/(s2) = 75, 000 Joules
EXAMPLE II
Find the elastic poterntial energy of a spring that follows Hooke’s Law when its stretched one meter
Assume the spring constant is equal to 10 N ⁄ m
figure images/3.png
PEspring = (1)/(2)kx2
PEspring = (1)/(2)⎛⎝10( N)/(m)⎞⎠(1 m)2
PEspring = 5 (kgm2)/(s2) = 5 Joules
Challenge:
Find the weight of the object
F = kx
F = ⎛⎝10 (N)/(m)⎞⎠(1 m)
F = 10 N