1. What are Machines?
Chapter 4

2. Is it a Machine? Examine the objects in the red bin.
Sort the objects into those that are machines and those that are not machines.
Answer the following questions as a table on the big paper.
How does each object that you classified as a machine functions?
How did you determine whether an object was a machine or not?

3. What are machines? Which of these is a machine: a robot or a shovel?
The answer: they both are!

4. What are machines?
Machine = any device that allows you to do __________ in a way that is _____________
To move a pile of dirt, you could use your hands or a shovel
Both methods require the same amount of work
The shovel just changes the way in which work is done
work
easier

5. What are machines? Machines make work easier by:
_________________ the amount of __________ you apply
Changing the ___________________ over which you apply your force
Changing the ____________________ of your force
Decreasing
force
distance
direction

6. How do machines make work easier?
Input and output force
Input = what ________ put in
You apply an input force
Your force moves the machine some distance
you

7. How do machines make work easier?
Input and output force
Output = what the ________________ does
The machine then applies a force
The machine’s force moves an object some distance
machine

8. How do machines make work easier?
Input and output work
Input work = input force X input distance
Output work = Output force X Output distance
Input work _________ Output work
equals
Distance
Force
Force OR
Distance

9. Decreasing the amount of force
Which would more easily remove the bolt?

10. 1) Decreasing the amount of force
Some machines cause the output force to become ____________ than the input force
Your weaker force gets _______________ to become a stronger force
greater
multiplied

11. 1) Decreasing the amount of force
How does this happen?
Work = Force X Distance
Work must stay the ______________
So, if force decreases, distance must ________________
Increasing the distance over which your force is applied causes your force to become stronger
same
increase
Smaller distance requires larger force
Larger distance requires smaller force

12. Which will allow you to accelerate the puck more easily?
Changing the distance
Which will allow you to accelerate the puck more easily?

13. 2) Change the distance
Some machines cause the output force to become ____________ than the input force
weaker

14. 2) Change the distance How does this make work easier?
You apply a great force but only over a _____________ distance
It is easier to apply a great force over a smaller distance than a larger distance
The smaller output force acts over a __________ distance, resulting in the same amount of work
small
larger

15. 2) Change the distance
Input distance
Output distance

16. What would be easier, to lift the barrel or to pull the barrel up?
Changing the direction of the force
What would be easier, to lift the barrel or to pull the barrel up?

17. 3) Changing the direction of the force
Some machines do not change force or distance
Instead, they change the direction of the force
Input and output force stay the same ________________, so why is this easier?
It is easier to ___________ down
It is harder to ___________ up
We use pulleys to lift things by pulling down on ropes: this is much easier
strength
pull
lift

18. Input force Output force

19. Activity
Read pages 116/117 in your textbooks to analyze 3 specific machines
Chop sticks, string/pencil/weight, and wrench/bolt