1. Work and Machines

2. Work equals Force times9
Seconds
Remaining
Energy
Velocity
Distance
Mass 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

3. Work is measured in Meters Pounds Joules Newtons Seconds Remaining 1 2
Seconds
Remaining
Work is measured in
Meters
Pounds
Joules
Newtons 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

4. Work and Machines
Describe what a machine is and how it makes work easier to do.
Relate the work input to a machine to the work output of the machine.

5. Which of these is an example of work being done on an object?
Seconds
Remaining
Holding a heavy piece of wood at a construction site.
Trying to push a car that doesn’t move out of deep snow.
Pushing a child on a swing.
Holding a door shut on a windy day so it doesn’t blow open. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

6. Machines Do Work A Machine is a device that changes force.
Machines make work easier to do in three ways.
Change the size of a force needed.
Direction of a force
Distance over which a force acts.

7. Seconds
Remaining
What do machines do?
Change the amount of force you exert or the distance over which you exert the force.
Increase the amount of work that is done.
Decrease the amount of work that is done.
Eliminate friction. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

8. Increasing Force
The upward force exerted by the jack is greater than the downward force you exert of the handle.

9. Increasing Distance
They will do the same amount of work. Doing the work over a longer distance allows them to use less force.

10. Changing Direction
When you use an ax to split wood, you exert a downward force as you swing the ax then it changes into a horizontal force that splits the wood apart.

11. How can a hockey stick be considered a machine?
Seconds
Remaining
It multiplies force.
It multiplies distance.
It changes direction.
It reduces friction. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

12. Pulling down on a rope to hoist a sail on a sailboat is an example of a machine.
Seconds
Remaining
Multiplying the force you exert.
Multiplying the distance over which a force is exerted.
Changing the direction in which a force is exerted.
Reducing friction. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

13. Input Force The force that you apply to the machine.
It is also known as the Effort Force.

14. Output Force The force that is applied by the machine.
It is also known as the Resistance Force.

15. A term that means the same thing as output force is
Seconds
Remaining
Input force
Resistance force
Effort force
Multiplying force 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32