Simple and compound machines Flashcards
What is a lever?
A lever is a firm bar resting on a fulcrum, used to move a heavy or firmly fixed load with one end when pressure is applied to the other.
Why are first and second class levers force multipliers?
They use force not speed.
Which body parts act as effort when our bones act as the levers?
Our arms!
Explain how a mechanical advantage can be obtained from simple machines such as levers, inclined planes, pulley systems and gears.
To find the ideal mechanical advantage of an inclined plane, divide the length of the slope by its height. With a lever, if the distance from the effort to the fulcrum is greater than the distance from the load to the fulcrum, then the lever has a mechanical advantage. The mechanical advantage of a pulley system is equal to the number of ropes supporting the movable load. Lastly, for gears, the mechanical advantage is given by the gear ratio.
When you bend your forearm upwards to lift a bucket of water, it acts as a lever.
Press see answer.
Where is the fulcrum?
The elbow.
Which muscle provides the effort?
The biceps muscle
What is the load?
The bucket of water.
Which type of lever is your arm acting as? Third class lever.
When you straighten your arms to do push-ups, your forearm acts as the lever.
Press see answer.
Where is the fulcrum?
Your feet!
Which muscle provides the effort?
Pectoral muscles
What is the load?
Your body weight.
Which type of lever is your forearm acting as? Second class lever.
Examples of speed multiplier and second class lever…
A door and tongs is a second class lever tongs is a speed multiplier.
Why are third class levers called speed multipliers?
Because a larger force is applied by the effort, the load travels further distance.
What is a ramp?
A tilted surface that goes from one level to another.
Ramps are inclined planes. List two other types of inclined planes.
Stairs and slides.
Ramp makes it easier to push or pull objects. What is the penalty for making this task easier?
It takes less force to move an object in an upward direction on an inclined plane than it does to lift the object straight up.
Why are inclined planes classified as force multipliers?
less force is needed to push the object
List as many eg of inclined planes as u can for wedges, screws and ramps.
Wedges: zipper, grated, sharpener, scissors.
Screws: slides.
Ramps: I can’t find any.
Which part of the circular doorknob is the wheel? Which part is the axle?
The knob is the wheel the part that opens it is the axle.
why is the circular doorknob called the force multiplier
By applying the effort on the wheel, the force is multiplied on turning the axle.
