Here are most all the concepts we have covered and learned about.
How can
you give friction the slip?
- slide
- ice rink
- curling
Do
rollers make work easier? Why? Rollers placed under a load reduce contact surface between the load and
the floor. This reduces friction. Less friction means that less effort is needed
to move the same object
Name 4
ways we use “rollers” everyday.
- Conveyor belt
- Toilet paper roll
- Steam roller
Rolling pin
Will a
load moved on rollers and a load moved on wheels be able to complete a slalom
race in the same amount of time? NO – the wheels will win because they are able to TAKE the load with
them; where you need to go with the load on rollers.
Machine: a device that helps us to do work.
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Force: a push or a pull action.
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Friction: is a force that slows down motion between two objects
that touch.
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There is LESS friction between smooth surfaces than
between rough surfaces.
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Work: is the result of a force moving an
object.
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Fixed Pulley System: a pulley that is stationary
and changes the direction of the force (makes it easier because you get to
pull down)
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Load: an object that needs to be “moved”
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Effort: the amount of force used.
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Gears: wheels with teeth that interlock to give off energy
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Fulcrum: the supporting point of a lever, also called a pivot
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Pivot: an object that allows something to “move” slightly
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A third class lever is a lever in which
the EFFORT is in between the LOAD and the FULCRUM.
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A first class lever is a lever in which
the FULCRUM is in between the LOAD and the EFFORT.
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A second class lever is a lever in which
the LOAD is in between the EFFORT and the FULCRUM.
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Two examples of a 1st class
lever: seesaw and prybar.
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Two examples of a 2nd class
lever: wheelbarrow and nutcracker.
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Two examples of a 3rd class
lever: tweezers and stapler.
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In a
wheel to wheel drive system, will both wheels turn in the same direction? No, the wheels turn in opposite
directions b/c they are touching.
In a
belt drive system, when do the wheels turn in the same direction? When the belt is around them in a “straight” line.
In a belt drive system, when do the wheels
turn in the opposite direction? When the belt is crossed in a
figure 8.
In a
belt drive system does the size of the driver wheel affect the rate at which
the driven wheel is turned? (“Change the
Driver” experiment) Yes,
smaller wheels will rotate more times than a big wheel will in one
rotation. Whereas if the small wheel is
the driver, the larger wheel will not go around a full rotation compared to one
rotation of the smaller wheel.
How are
dominoes like simple machines? They transfer energy from one to another.
In a
gear drive system, do gears of different sizes affect the speed of the driver
gears (“Gear Together” experiment) ___________________________________________
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Does
changing the size and number of gears in a system affect the speed and
direction of the gears? _______________________________________________________
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Does
changing the position of the fulcrum affect the force needed to carry a load? Yes, you need more force to lift
a load as the fulcrum gets closer to the effort.
Does
changing the location of the effort on a third class lever affect its
performance? Yes, a 3rd
class lever is most effective when the effort is close to the load.
In a 2nd
class lever, as the load moves closer to the fulcrum, is more or less effort
required to lift the load? As
the load gets closer to the fulcrum, there is less effort required.
Do
pulleys make raising an object easier? YES! – b/c I can use my body
weight.
Will
the use of a pulley reduce the amount of force required to lift a load? NO – but it changes the
direction (pulling down)
Will a
moving pulley affect the effort required to lift a load? (Single Movable Pulley experiment) YES! – it reduces the effort in half. –refer to comparison
sheet.
Does a
fixed & movable pulley system affect the effort required to life a load?
(Single Fixed & Single Movable Pulley experiment) HINT HINT HINT *** be
able to draw a labeled picture of this pulley system** S.M. – reduces the
effort; S.F. – changes the direction
Will
the placement of the axle in the wheels change the efficiency of the vehicle? Yes. The best place for the axle is in the middle
of the wheel so that the wheel turns evenly.
Where
will the largest movement in a wheel and axle occur – in the axle or in the
wheel? WHY? The axle has
to work harder b/c it is smaller than the wheel; therefore it rotates more
times than the wheel does in one rotation.
