Work and Energy
What is an example when an object has gravitational potential energy
book on shelf, man hanging off a cliff .... anything off the ground
What is the unit for efficiency?
Percentage (%)
What is Kinetic Energy?
the Energy of Motion
What is potential energy.
Energy when an object is still; Energy related to position.
What is the formula for work?
W=Force X Distance
Power is the rate at which energy is converted. What is the equation used to find power?
Power (Watts) = Energy (Joules)/Time (secs)
Rodney used a gallon of gas to go 25 miles. Cassie used 2 gallons of gas to go 70 miles Which car is more efficient?
Cassie's car is more efficient because she goes 35 miles per gallon of gas.
What is the formula for KE?
KE= .5(mass)(v2)
Describe the equation for gravitational potential energy?
mass X gravity X height
When is work done and not done when holding a barbell over your head?
When the barbell is being lifted but not at the top when it is still.
What types of energy are involved in a lit flashlight?
Chemical, Electrical, Mechanical
What is the formula for efficiency?
e = W(out)/W(in) x 100
What is the Kinetic Energy of a 10 Kg ball moving at 5m/s ?
125 J
What type of energy is involved in a rubber band that's pulled back?
Elastic Potential
What is the unit for Work and Energy?
Joule
A hydroelectric dam involves what kinds of energy?
Kinetic, mechanical, electric, Gravitational Potential
Who does more work? Spencer walking up the 20 m high staircase carrying his backpack using 10 J of energy, or John running up the same staircase carrying a backpack using 3 J of energy?
Spencer does more work.
What is the Kinetic Energy of a 15 Kg bowling ball sitting on the shelf ?
O J
What is the potental energy of a 3 Kg book on Earth on the ground?
0 J
1) How much work is done if you push a 200N crate for 4 meters?
800 Joules or N*m
What is the law of conservation of energy.
Energy is never created, lost, or destroyed, it just changes form.
List whether the following items are simple or compound machines:
- Bicycle
- Wedge
- Inclined plane
1. Compound
2. Simple machine
3. Simple machine
What is is the Kinetic Energy of a 300 Kg dog running at 3m/s ?
1350 J
An object has a mass of 250 kg. It is 20 m above the ground. What is the GPE?
250kg x 9.8 x 20m = 49000 J