simple machines and what they do to force for grade 3

2. Something that makes work
easier to do

3. Example: It's easier to lift & carry
a rock with a wheelbarrow that to
carry it with your hands

4. - They are machines with few or no
moving parts

5. - It is a straight bar that moves on a fixed
point "Fulcrum”
Examples:
Seesaw
(1) Lever
Load
Fulcrum

6. Load
Fulcrum
-Pressing down on a lever, lifts up the load.
-Levers change how much force you need to move something.

7. What does the lever do?
- It makes it easier to lift loads.
What happens to the force?
- The force becomes less.
- And the direction of force
changes to the opposite.

8. (2) Pulley
- It is a kind of lever that uses a wheel & a
rope to lift an object
Examples:
When you pull down one end of the rope, the
other end rises up
Wheel
Rope

9. What does the pulley do?
- It makes it easier to lift loads.
What happens to the force?
- The force becomes less.
- And the direction of force
changes to the opposite.

10. (3) Wheel & Axle
- It is a kind of lever that uses a wheel that
moves around an axle.
Examples:
A Ferris wheel
Wheel
Axle

11. What does the wheel and
axle do?
- It makes it easier to move loads.
What happens to the force?
- The force becomes less.

12. A Door knob
A Wheel barrow

13. A shopping cart
A Mouse wheel

14. It is a simple machine with flat & inclined
surface which reduce the force needed to
move an object.
Example:
A Ramp
- It is easier to slide a heavy box on an inclined
Plane than to lift it up.
(4) Inclined plane

15. What does the inclined plane
do?
- It makes it easier to carry loads up.
What happens to the force?
- The force becomes less.
- And the distance becomes more.

16. - It is an inclined plane wrapped onto a spiral.
- "A screw changes a turning force into a
downward force“ as we turn the screw,
it moves down.
Example:
{It is easier to turn a screw than to pound a nail}
(5) A screw

17. What does the screw do?
- It makes it easier to fix loads.
What happens to the force?
- The force becomes less.
- And the direction of force
changes from turning to
downwards.

18. An Auger is a giant screw

19.  It is a simple machine that splits objects
apart.
"A Wedge changes a downwards force into
sideways force"
Examples:
The Head of an Ax The Knife
(6) A Wedge

20. What does the wedge do?
- It makes it easier to cut loads.
What happens to the force?
- The force becomes less.
- And the direction of force
changes from downwards to
sideways.

21. They are made of two or
more simple machines
together.
Compound machines

22. 2 wedges
Fulcrum
“fixed point”
2 levers
A pair of scissors is
a compound
machine that is
made of two wedges
& two levers

23. Pulley Wheel & axle
A bicycle is a compound
machine that is made of
pulleys & wheel & axle.

24. Wheel & axle Fulcrum
Load
A Wheelbarrow is a
compound machine that
is made of a lever &
wheel & axle