1. QOD #103
Calculate the POTENTIAL ENERGY of a ball with a mass of 2 kg, sitting on a ledge 3 meters high. (PE=mgh)
PE=58.8 Joules
2. Calculate the KINETIC ENERGY of that ball as it falls with a velocity of 15m/s. (KE=0.5mv2)
KE = 225 Joules
Both units are in Joules!

2. Work
Work – The amount of energy used as a force moves an object over a distance.
Ex. Lifting weights
It is not considered work if there is no movement.
Work is measured in Joules (J)

3. Work Equation
W = F d
Work (J) = Force (N) x distance (m)

4. Ex1: A student pushes a desk 2 m using a force of 25 N
Ex1: A student pushes a desk 2 m using a force of 25 N. How much work does the student do? W = Fd W = 25 N x 2 m W = 50 Joules (J)

5. Ex2: Jerry drags Tom 3 meters across the floor with a force of 15N
Ex2: Jerry drags Tom 3 meters across the floor with a force of 15N. Calculate Jerry’s work. W = Fd W = 15 N x 3 m W = 45 J

6. Marble Launcher
Question: How does the force applied to the marble affect the work done on the marble? Purpose: Calculate work.

7. IV: force applied to the marble DV: distance marble travels Constants: pressure on lever, size/mass of the marble, Prediction: I think…

8. The Work Done on a Marble w/ Different Forces Applied
Distance (Trial 1)
Distance (Trial 2)
Distance
(Trial 3)
Average Distance (m)
Work (Joules)
3 N
6 N
9 N
12 N
15 N

9. Procedures: Jobs: Pull the lever down to the first notch, 3 N.
Place the marble in the launcher.
Make sure everyone is out of the way & ready! Everyone must wear googles!
Push lever & marble will release.
Estimate the distance the marble went.
Someone must be ready to catch the marble & roll it back to the launcher. Record the distance.
Jobs:
Marble Launcher
Marble catcher
Distance reader
Recorder

10. QOD#104
Calculate the amount of work to push a box 20m with a force of 30N. W = Fd W = 30 N x 20 m W = 600 J

11. Simple Machines
Machine – An object that makes doing work easier. Simple Machines – do work using only one movement.

15. Lever Screw Inclined Plane Pulley Wedge Wheel & Axle Sketch Examples
(at least 3)
Used for…

16. What kind of simples machines are the following?

17. Goonies Rube Goldberg
Ok-Go! Video

18. Identify the simple machines in a pair of scissors.
QOD#105
Identify the simple machines in a pair of scissors.

19. Identify the simple machines in a bicycle.
Pulley
Wheel & axle
lever

20. QOD#106
Calculate the force of an 18kg bowling ball falling off of a building.
2. Calculate the amount of work to push a box 20m with a force of 30N.
W = Fd
W = 30 N x 20 m
W = 600 J
18kg x 9.8m/s² = N
F = ma

21. QOD#106
What are the following units for…
m/s N
km/h north kg J
m/s2

22.
QOD#54

23. Calculating Work Object Action Force (N) Distance (m) Work (J) Book
Dragged across floor
50 N
5 m
500 J 1. 2. 3. 4.