Energy
Everything that performs work is said to have
energy. Since work and energy have a direct relationship, so energy is measured
in the same unit , that Joules (J) or calories (cal).
1 J = 0.24 calories (cal)
1 calorie = 4.2 J
1 kcal = 4,200 J, to be exact 1 Kcal = 4,180 Joules
*Energy is the ability to perform work*
The followings are some forms of energy: Sound Energy, Spring Energy, Chemical Energy, Light Energy, Electrical Energy, Nuclear Energy, Mechanical Energy, Kinetic Energy, Potential Energy
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WHAT IS POTENTIAL AND KINETIC ENERGY
(FORMULA)
Potential Energy is the energy possessed by an
object because of its relative position.
Formula:
Potential Energy = Mass x Gravity x Height
PE = M x G x H
Kinetic Energy is the energy possessed by an object
because of its motion.
Formula:
Kinetic Energy = 1/2 x Mass x V^2
KE = 1/2 x M x V^2
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EXAMPLES OF POTENTIAL AND KINETIC ENERGY:
1. A coconut with a 2 kg mass is hanging at 6m high. If gravitational acceleration g = 10 m/s, determine the potential energy of the coconut relative to the ground.
Solution:
Given: m = 2kg
h = 6m
g = 10 m/s
PE = M x G x H
= 2 kg x 10 m/s x 6 m = 120 kg m/s
= 120 Joules
2. An athlete is practicing himself by running with a 5 m/s speed. if he has a 40 kg mass, what is his kinetic energy?
Solution:
v = 5 m/s
m = 40 m/s
KE = 1/2 mv^2
= 1/2 x 40 kg x ( 5 m/s ) ^2 = 20 kg x 25 m/s
= 500 Joules
3. A 5 kg mass object is 8 m from the ground. If the gravitational acceleration is 10 m/s, the potential energy possessed by the object is?
Solution:
m = 5 kg
g = 10 m/s
h= 8 m
PE = M x G x H
PE= 5 kg x 10 m/s x 8 m
PE= 400 Joules
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