Potential Energy
A push or pull that causes motion
Work
What is the formula for Kinetic Energy?
KE=1/2mv2
What is the formula for potential energy?
PE=mgh
PE=mgh
2. What is the kinetic energy of that same dog running with a speed of 4 m/s?
KE = 1/2mv2
3. What is the Total Mechanical Energy (TME) of the system?
TME = PE + KE
1. PE = mgh = (50)(9.8)(5) = 2450 J
2. KE = (1/2)mv2 = (1/2)(50)(4)2 = 400 J
3. TME = PE + KE = 2450 + 400 = 2850 J
This type of energy is referred to as the energy of an object in motion
Kinetic Energy
The amount of work done over time
Power
What is the kinetic energy of a car with a mass of 1000 kg moving at a speed of 25 m/s?
KE=1/2mv2
312500 J
What is the numerical value of gravity with units?
9.8 m/s2
This term says energy cannot be created or destroyed
Law of Conservation of Energy
What is the work done by a plane flying with a force of 5000 N over a distance of 100 m?
500000 J
What is the Kinetic Energy of a 90 kg person running at a speed of 3 m/s?
KE=1/2mv2
405 J
What is the Potential Energy of a 50 kg box sitting on a 15 m shelf?
7350 J
When energy is "lost" it is usually lost as this type of energy
Thermal Energy
A biker pedaling with 200 J of work over 5 seconds
OR
A rollerblader skating with 225 J of work over 6 seconds
The biker (40 Watts)
What is the speed of a cat with a KE of 500 J and a mass of 20 kg?
KE=1/2mv2
7.07 m/s
A 80 kg person is standing on a roof with a potential energy of 50000 J. How high is the roof?
63.7 m