Name :
WORK AND MACHINES
Objectives	Assignments
1.  Define work and write the equation for work  2.  Define power and write the equation for power  3.  Solve equations using power and work 4.  Understand how work and energy are related 5.  Explain how machines make doing work easier 6.  Describe the 6 simple machines and give examples of each 7.  Calculate the mechanical advantage of a machine 8.  Define efficiency 9.  Describe the 3 types of levers with respect to the fulcrum; give examples 10.  Distinguish between a fixed and moveable pulley 11.  Describe a block and tackle 12.  Calculate the mechanical advantage of inclined planes 13.  Explain how the wheel and axle works	Problem Set:  Work Problem Set:  Power Vocabulary:  Work and Machines Article:  Levers and Body Parts (Lab) Lever Lab (Lab) Pulleys and Inclined Planes

Review Questions

1.  Identify the simple machine described:

An inclined plane wrapped in a spiral around a post __________________________
Has a pivot point between the load and input force __________________________
A sloping flat surface used to raise objects. __________________________
An inclined plane with one or two sloping sides. __________________________
Can be fixed or moveable, consists of a rope wrapped around a wheel__________________________
A bar that is free to pivot around a fixed point. __________________________

2.  Give an example of each type of simple machine

Wheel and Axle  __________________________ Screw  __________________________
Inclined Plane __________________________ Lever __________________________
Pulley __________________________Wedge__________________________

3.  Identify the parts of this lever
A_____________________
B____________________
C _____________________
4.  What type of lever is pictured? ________________

5.  If you place a 100 N load at point A on the lever.  What force would be needed to balance it at point C.  No calculations necessary, use your “best guess”.
a.  100 N                 b. 200 N                  c.  50 N

6.  If B was perfectly centered, what force would balance a 100N load at point A? a.  100 N          b. 200 N               c.  50 N

7.  Draw a diagram of a class 2 lever and identify the fulcrum, load and effort.
Name a tool that acts as a class 2 lever: ____________________________

8.  Draw a diagram of a class 3 lever and identify the fulcrum, load and effort.

     Name a tool that acts as a class 3 lever: ____________________________

9.  Define WORK: _________________________________________________
What is the equation used to calculate work? _________________________
What unit is work measured in? _____________

10.  Define POWER: ________________________________________________
What is the equation used to calculate power? _________________________
What unit is work measured in? _____________

11.  Examine the two pulley designs…

Which one has the greatest MECHANICAL ADVANTAGE? _____

If 100 N of force are required in design A (F1), how much force would be necessary for design B (F2).  The distance of the rope in design B is double that of design A.   _________

Which design is a Block and Tackle? ______

Which one is a fixed pulley? _______

 

12.  What is MECHANICAL ADVANTAGE? __________________________________________________
How is it calculated? _____________________________________________________________

What can increase the mechanical advantage of a wheel and axle? ____________________________
What can increase the mechanical advantage of an inclined plane? ____________________________
What can increase the mechanical advantage of lever? _________________________

13. You will also have problems to do for the test.  Here are two samples.

A)  How much work is done pushing a block 200 m with a force of 30 newtons?

 

B)  You push a stroller a distance of 10 meters, the amount of work expended is 2500 J.  What is the force used in pushing the stroller?

 

C)  A motor has a power of 300 W.  How much work can be done by this motor in 30 seconds?