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 Advantage4 / 100N / 6cm / 200cm / 18N / 5.6 / 33.3
12 / 100N / 18cm / 200cm / 27N / 3.7 / 11.1
20 / 100N / 30cm / 200cm / 30N / 3.3 / 6.7
22 / 100N / 33cm / 200cm / 31N / 3.2 / 6.1
30 / 100N / 45cm / 200cm / 40N / 2.5 / 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.