Name _____________________________
Date _________
Class _______________
Simple Machines, Mechanical Advantage, and Efficiency Study Guide
Section 1 Vocabulary
Please use complete sentences to answer the following questions.
1. What is the difference between input and output force?
Input force is force exerted by humans or another machine onto a machine and output force is force
exerted on an object/machine by a machine
2. How does a machine make work easier?
The three ways machines make work easier is by changing the amount of force, the distance, and the
direction.
3. If the output force of a simple machine increases, would the mechanical advantage increase,
decrease, or stay the same and why?
The mechanical advantage would increase because the mechanical advantage of a machine is the output
force ÷ input force.
4. What is the efficiency of an ideal machine and what factor decreases efficiency for actual machines?
The efficiency of ideal machine is 100% and the factor that decreases the efficiency of actual machines is
friction.
5. What are the six simple machines? Then give an example of how it makes your life easier.
The six simple machines are inclined planes, wedges, screws, levers, wheel and axle, and pulleys. A
wheel and axle is part of a car in a few ways; two of the ways are with the steering wheel and the tires.
The car enables us to get where we need to be and the care does a majority of the work.
6. Which of the three types of levers has a mechanical advantage of less than 1? Is this machine still
making working easier?
The type of lever that has a mechanical advantage less than 1 is a third class lever. Even though the
mechanical advantage is less than 1 the machine is still making work easier by increasing the output
distance.
Section 2 Calculations
Please write down the equation for mechanical and ideal mechanical advantage, and then complete
the table below.
8. Mechanical Advantage = ____________________Output Force ÷ Input Force ____________________
9. Ideal Mechanical Advantage = _____________Length of Incline ÷ Height of Incline ________________
10. Complete the table below.
Number
of
Books
Output
Force
(N)
Height of
Incline Plane
(cm)
Length of
Incline
Plane (cm)
Input
Force (N)
Mechanical
Advantage
Ideal
Mechanical
Advantage
4
12
20
22
30
100N
100N
100N
100N
100N
6cm
18cm
30cm
33cm
45cm
200cm
200cm
200cm
200cm
200cm
18N
27N
30N
31N
40N
5.6
3.7
3.3
3.2
2.5
33.3
11.1
6.7
6.1
4.4
11. If you were building a wheelchair access ramp, which height would you choose and why? Consider
the different factors of building a ramp.
Any of the five trials can be argued to be the best for a wheelchair ramp. The trial with 4 books has the
highest mechanical advantage which means people using this ramp would have to exert the least
amount of effort. If you chose the fifth trial that had a height of 45cm, this may also be the best option
if the area where the ramp is built is small.
12. Why does the mechanical advantage never exceed the ideal mechanical advantage?
Mechanical advantage can never exceed ideal mechanical advantage because ideal mechanical
advantage measures 100% efficiency of a simple or compound machine. Actual mechanical advantage
takes into consideration friction, which is a force acting against the machine. For actual mechanical
advantage and ideal mechanical advantage to be equal your machine must be in a frictionless
environment.
Section 3 Identify
Identify which simple machine each item is an example of.
13. Knife
________Wedge_____________
14. Wheelchair Ramp
________Inclined Plane________
15. Car Steering Wheel
________Wheel & Axle________
16. Hockey Stick
________Lever_______________
17. Water bottle Cap
________Screw______________
18. Crane Lift
________Pulley______________
Section 4 Challenge Questions
Answer the following questions in complete sentences.
19. What does it mean if mechanical advantage and ideal mechanical are identical? Explain.
It means that your simple machine is in a frictionless environment. Mechanical advantage takes into
consideration the friction occurring, which can be from the result of wear and tear, scrapes, or any
damage that increases surface area.
20. What is the mechanical advantage of a machine that only changes the direction of the force
applied?
The mechanical advantage is 1 because only the direction changes, the input force and output force
remain the same.