The Learning Station
Science Grade 8
14
1. Complete the following and justify your answer.
I.
A fork is an example of:
a)
b)
c)
d)
Pulley
Wedge
Wheel and axle
Lever
Explain: d, because the fork has an input and output force with the the
bottom of the fork as a fulcrum.
II. A roller skate is an example of a:
a)
b)
c)
d)
Wheel and axle
Wedge
Lever
Screw
Explain: a, pretty obvious, it has a wheel an axle.
III. A ramp is an example of a/an:
a)
b)
c)
d)
Lever
Inclined plane
Wedge
Pulley
Explain: b, pretty much is THE example for an inclined plane.
IV. A seesaw on the playground is a:
a)
b)
c)
d)
Lever
Inclined plane
Pulley
Screw
Explain: a, first class lever with fulcrum in the middle.
V. The bottom of a light bulb would be considered:
a)
b)
c)
d)
Lever
Inclined plane
Wedge
Screw
Explain: d, since it’s ridged. It can be turned clockwise or counterclockwise for locking or unlocking.
VI. You would use a pulley to:
a)
b)
c)
d)
Cut food
Hold pieces of wood together
Help guide a sail on a sailboat
Elevate boxes
Explain: d, raise objects or lowering them with reduced
effort.
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2. How far away from the fulcrum must the red 5kg mass be in order to just lift the
10kg mass 10 metres away from the fulcrum?
Show all your work (Formula and units, devil’s in the detail!)
3. A How far away from the fulcrum must the red 5kg mass be in order to just lift the
10kg mass 30 metres away from the fulcrum?
Show all your work (Formula and units, devil’s in the detail!)
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4.
Also, state
the type of
simple
machine to
which it
belongs.
A) Axe: a wedge is used to cut.
B) Scissors: 1st class lever, use to cut.
C) Wrench: 2nd class lever, used to tighten or loosen screws.
D) Pencil sharpener: Complex machine: 2nd class lever and wheel and axle. Sharpening pencils.
E) Wheel barrel: 2nd class lever, carrying and unload heavy objects.
F) Broom: 3rd class lever, sweeping.
G) Crow bar: 1st class lever, prying objects out.
H) Manuel hand drill: Comlpex machine: wheel and axle, screw and 2nd class lever. No surprise: drilling.
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5.
A machine is any technological object composed of one or many components able to use energy to perform work. It can
be a simple machine or a complex machine made of many several simple machines.
Door knob, light switch and door hinge.
6.
Explain: 1st class lever, motor force and load are on opposite sides of the fulcrum or pivot.
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7.
Pivot
Load
Load
Effort
Load
Pivot
Pivot
Effort
Effort
Load
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8.
C) Vice grip is used to hold or support objects that you may wish to deform: bend, drill,
straighten, etc.
D) To make holes in different surfaces.
E) To make holes in order to pull the cork out.
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9.
A) Lever
B) Lever
C) Gear
D) Wheel
E) Lever
F) Screw
G) Lever
H) Wheel
10.
Explain: a, a screw is like an inclined plane; it reduces the
amount of force needed to go forward.
11.
Explain: a, a is the best possible answer.
You could have chosen b, but it depends
on the object you’re using. Same for c.
12.
Explain: d, the others are all examples of simple machines.
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13.
Explain: b, effort from chemical energy stored in the muscles helps in performing
the motor force needed for an action. The elbow, the wrist and the shoulder can
all be fulcrums.
14.
Explain: d, in this case, the load arm is much smaller and therefore, less effort is needed to lift the
load.
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