Chapter 12 Post-Test
Terms in this set (25)
A screw is also what kind of simple machine?
The wedge & screw is also part of which simple machine family?
Fixed, movable, and block & tackle are examples of which simple machine?
What is the fixed point that a lever pivots around?
When you pull_____ the object on the pulley goes_____.
The steering wheel of a car is known as what simple machine?
wheel & axle
Real machines have an efficiency of less than 100% because some work is wasted to overcome?
You're holding your dog's leash and trying to stand still as he pulls on the leash at an angle. You move forward. ________________ his force does work on you.
A flat, sloped surface is called a(n)___________________.
The threads of a screw act like a(n)____________________.
A screwdriver and a doorknob are examples of a(n)___________.
wheel & axle
The amount of work done on an object is found by multiplying_______________.
force times distance
One way a machine can make work easier is by___________________.
Which of these is an example of a simple machine from the inclined plane family?
Which is the best scientific definition of a machine?
A machine makes work easier by changing force, distance, or direction.
A waiter carries a 5-newton tray of food while he walks a distance of 10 meters. Is work done on the tray? Why or why not?
No; when the force is not in the same direction as the direction of motion, no work is done.
What will happen to the efficiency of a bicycle after the gears have been cleaned and the chain has been oiled?
The efficiency of the bicycle will increase.
What happens to the efficiency of a bicycle as it gets rusty? What must you do to maintain the same amount of output work?
The efficiency of the bicycle will decrease. To maintain the same amount of output work, I must pedal the bicycle harder.
What are some examples of ramps that you have seen or used in your everyday life?
wheelchair ramps, skateboard ramps, highway on-ramps
Name 1 way inclined planes and screws are similar and 1 way they are different.
Both involve sloped surfaces, but screws move and are wrapped around cylinders
How does an inclined plane help you do work?
An inclined plane allows you to exert your input force over a longer distance.
Explain how simple machines make our lives easier?
Simple machines make our lives easier by doing the "work" for us. The amount of force that we have to use is decreased by using simple machines.
What is the difference between compound machines & simple machines?
A compound machine consists of more than one simple machine combined. A simple machine is only one, such as a lever, pulley, screw, wheel & axle, inclined plane, or wedge.
Explain what simple machines the Egyptians used to build the pyramids and how they used those simple machines.
They used a giant inclined plane to lift the heavy stones up the pyramid. They used wedges to shape/form the stones. They used wheel & axles for the wagons to carry stones/items up the inclined plane.
A paper cutter is a compound machine. How does it make cutting paper easier? What simple machines make up the paper cutter? Describe how they interact.
The paper cutter lets me cut in straight lines neatly and easily. It contains a lever and a wedge. I push down on the lever, which pushes the wedge down through the paper.
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