WorksheetsWork and Efficiency
Total questions: 22
Worksheet time: 35mins
To find the amount of work done on an object, you must
divide force and power
divide force and distance
multiply force and power
multiply force and distance
Which of the following is NOT an example of work being done?
Lifting a weight above your head
Carrying a box up the stairs
Pushing furniture across the room
Pushing downward on an unmoving table
How much work is done by lifting an object with a weight of 250 N a total of 2 m off the ground?
125 J
125 W
500 W
500 J
Efficiency is a measure of
how much work is done per second
how much work is output versus to how much work is input
how much power is used per second
how much power is output versus how much power is input
The SI Unit for Energy is
Joule
Newton
Calorie
Watt
What is the SI unit for measuring work?
Watt
Joule
Pascal
Newton
Anything that makes work easier is a ______
force
machine
watt
bad idea
How many types of simple machines are there?
3
4
5
6
A machine will always do ___ work on an object than the user does on the machine
more
less
the same amount
Most machines are close to 100% efficient.
True
False
How do you calculate mechanical advantage?
Divide the force put out by the force put in.
Multiply the force put out by the force put in.
Add the force put out by the force put in.
Subtract the force put out by the force put in.
What is the efficiency of a car that has enough fuel to drive 600 miles, but only actually drives 150 miles?
25%
4%
400
.25
Calculate the amount of work done if you use a 100N force to push a 50kg box 5m across the kitchen floor.
250 J
500 J
5000 J
50,000J
If a machine exerts a force of 250 N on an object and no work is done, what must have occurred?
The machine has broken
The object has not moved
The object has gained momentum.
The object has moved, but then stopped
A man has an air conditioner he wants to load into the back of his truck. Instead of lifting the air conditioner and carrying it to the truck, he improvises a ramp. He takes a board that is 3.6 meters long and places one end of it in the back of his truck, 1.2 meters off the ground. He leaves the other end of the board on the ground. He places the air conditioner on a dolly and pushes them both up the ramp and into the truck. What is the mechanical advantage of the ramp?
3.0
2.5
4.32
4.8
Which two simple machines are found in a pair of scissor?
screw and lever
lever and wedge
screw and inclined plane
pulley and ramp
An engine has an inout of 5000 W. The useful output is 4000W. Calculate its percentage efficiency.
90%
80%
75%
85%
A washing machine uses 250J of electrical energy to produce 125J of useful energy. How efficient is it?
5%
50%
55%
100%
