Topic 1
A seesaw is this type of lever
Class 1 Lever
What is the wheel?
What is work?
Work is the transfer of energy from one place to another.
What is the unit for work and energy?
What is the Joule?
What is the advantage of sliding a fulcrum closer to the load in a class 1 lever?
POWER
Nut crackers combine two of these levers
Class 2 levers
When the effort force is on the small axle of a wheel, we get this kind of advantage
What is a speed advantage?
This is the energy of moving things
What is kinetic energy?
Give an example of a class 3 lever
VARIOUS
Name both ways a driver gear can cause a follower to go the same direction
Sprocket and chain
By having a 3rd gear in the train
What is the formula for work?
W = F x D
Work is equal to force times distance
What is the name for a combination of fixed and moveable pulleys?
This is the stored energy held within an object raised off of the ground.
What is gravitational potential energy
T/F a machine can be 100% efficient
False
When is friction useful?
Anytime we do not want to slip
A hockey stick and broom are examples of this lever
Class 3 lever
When the effort force is on the larger of the two rounded parts attached to an axle, we get this kind of advantage
What is a force advantage?
This is the easiest way to increase efficiency
What is reducing friction?
Give an example of a 2nd class lever
VARIOUS
What is the advantage of sliding the fulcrum closer to the effort force with a 1st class lever?
SPEED
If a force of 500N on a lever produces a force of 30 000N on the load, what is the Mechanical advantage of the lever?
30 000 / 500 = 6
This means we get 6 times the force out of the lever
What is the speed ratio if the driver gear has 6 teeth, and the driven gear has 36 teeth?
What is 0.16 repeating. This means the driven gear goes 0.16 times as fast, or under 1/5th of the speed the driver goes.
If a toaster uses 1000 J of energy to cook a piece of bread, but only 750 J of heat are produced, what is the efficiency of the toaster?
750/1000 x 100 = 75% efficiency. Where does the rest of the energy go?
What is the force advantage when a driver gear with 5 teeth turns a driven gear with 45 teeth?
45/5 = 9 Which means we gain a force advantage of 9x
Where does energy lost by a system typically go? (need both answers)
Heat and sound caused by friction