Work and Energy
Define: Work
The change in energy of an object done by applying a Force to an object causing it to have displacement
Give an example of an object with gravitational potential energy
Answers Vary (e.g, A book on a table)
What is the SI unit for power?
Watts
How much work is done if Zion pushes a force of 600N against the wall for 3mins?
0J (No work is done)
What is the formula for work?
W=F(D) D=Distance
Which form or forms of energy does a ball falling through the air possess
Gravitational potential energy and kinetic energy
What is the difference between energy and power?
Work and energy don't involve time, but power does
Is work done when caring a book at the same height while walking?
No
What work is done when a pin ball being pushed into action by a spring.
Mechanical and kinetic (maybe gravitational)
What is the formula for power?
P=W/T
What is the formula for gravitational potential energy?
PE=mgH
What is an example of when force is applied but no work is done?
push on wall or other
A hydroelectric dam involves what kinds of energy.
Kinetic, mechanical, electric
Who does more work? Joe walking up the 20 m high staircase carrying his backpack in 10 seconds, or John running up the same staircase carrying a backpack in 3 seconds?
They do the same
Where is kinetic energy of a pendulum bob on a string the highest?
At the bottom (middle position)
An object has a mass of 250 kg. It is 20 m above the ground. What is the PE?
49000J
1) How much work is done if I push a 100N crate across the floor with a force of 50N for a distance of 1m?
1) W=F(D) 50(1)=50 J
What is the law of conservation of energy.
Energy is never created, lost, or destroyed. Only transformed.
A runner runs up a flight of stairs using 200J of work in 10 sec. What is the Power?
Power: P=W/T= 20 Watts
What happens to the kinetic energy if you double velocity and triple the mass?
Proportional reasoning-KE=1/2MV^2=3M(4V)=12KE
A 75 kg skier is at the top of 85 m tall hill. How much PEG does the skier have at the top?
PE=62539J