Student Name:



Student Name: ________________________

Student Resource 3.1.6

Mechanical Advantage Worksheet

Simple machines (lever, pulley, wedge, screw, inclined plane, wheel and axle) often are combined to create complex mechanical machines. Simple machines apply mechanical advantage to typically move an output force (load) with an input force (effort), less than that of the output force. The general equation for mechanical advantage is shown below:

Mechanical Advantage (MA) = Load (R)/Effort (E)

Each simple machine possesses its own equation for mechanical advantage. The formula for mechanical advantage for each simple machine is represented below:

|Lever |Inclined Plane |

|MA = |MA = |

|Length to Effort (LE)/Length to Load (LR) |Length of Plane (L)/Height of Plane (H) |

|Wheel and Axle |Pulley |

|MA = |MA = |

|Radius of Effort (LE)/Radius of Load (LR) |number of ropes that support the pulley |

|Wedge |Screw |

|MA = |MA = |

|Length of slope (L)/thickness of wedge (H) |Circumference (C) / pitch (p) |

Practice

Using the equations above, calculate mechanical advantage for the following examples. Be sure to show your work.

1. What is the mechanical advantage of the system pictured on the right?

2. If the load is 100 pounds, how much effort is required to pick up the load?

3. What is the mechanical advantage of the system pictured on the left if the diameter of the wheel is 15 feet and the diameter of the axle is 3 feet?

4. If Mrs. Jones can only pull with 25 lbs of force, how much weight can she lift using the wheel and axle system from question 3?

5. If we build a ramp in Tech Ed class that is 2 feet high and the length of the ramp is 30 feet, what is the mechanical advantage?

6. How much effort force would someone need to push a 45 pound box up the ramp from question 5?

7. Jose and Suzette construct an arm where the effort is located 10 inches from the fulcrum and the load is 25 inches from the fulcrum, what is the mechanical advantage of the arm?

8. Find the mechanical advantage and the maximum separation load for a wedge used to split the object shown. The wedge has an incline length of 8 inches, an overall height of 2 inches. The effort load applied is 60 pounds.

9. Using a 1-inch diameter screwdriver, students in the lab used the screw shown to fasten two objects together. What is the mechanical advantage of the screw?

3/4 - 10 UNC

Application

One student group has decided to design a device where a toy car (10 grams) must apply a force to lift a 50 gram weight 2 inches in the air. What simple machine could the group use and what mechanical advantage would they need to achieve their goal? Place your answer, including a sketch of the device, in the space below.

Reflection on the Design Problem

Write your response in the space below using complete sentences.

8. How could simple machines and mechanical advantage help me in designing my device for the “Rube Goldberg activity?

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Formula Sheet

Mechanical Advantage = Load/Effort

Mechanical Advantage of a Pulley = number of strands

Mechanical Advantage of a Wheel and Axle = Radius of Effort/Radius of Load

Mechanical Advantage of a Wheel and Axle = Radius of Wheel/Radius of Axle

Mechanical Advantage of an Inclined Plane = Length of Plane/Height of Plane

Mechanical Advantage of a Lever = Length to Effort/Length to Load

Circumference of Wheel (C) = (pi) * (wheel diameter) = πd

S = Distance traveled in one revolution

Pitch = 1/ # of threads per inch

Student Name: ________________________

Student Resource 3.1.5

Ohm’s Law and Basic Circuits Worksheet

Electrical and electronic technologies utilize Ohm’s law to explain the relationship between voltage, current and resistance. The formula for Ohm’s Law is represented below:

Ohm’s Law = V = I x R

V = voltage (units=volts) I = current (units=amps) R = resistance (units=ohms)

Practice

Using Ohm’s Law, solve the following problems. Be sure to show your work.

1. A nine volt battery supplies power to a cordless blow dryer with a resistance of 18 ohms. How much current is flowing through the blow dryer?

2. A 110 volt wall outlet supplies power to a black light with a resistance of 4400 ohms. How much current is flowing through the black light?

Designers and engineers use ohm’s law to determine the specific electrical and electronic components needed in a circuit, depending on the desired purpose. Basic circuits contain four parts (Figure 1): power source, conductor, control, and load (output).

Figure 1

[pic]

Series and parallel circuits are the common types of circuits. See Figure 2 for images of both series and parallel circuits.

Figure 2

[pic] [pic]

Series Circuit Parallel Circuit

3. Compare and contrast the images above using the Venn diagram below. What is similar, what is different?

[pic]

Application

4. What do you think would happen if a light burns out in a series circuit?

5. What do you think would happen if a light burns out in a parallel circuit?

Reflection on the Design Challenge

6. What might you use as a load (output) for your Rube Goldberg device? Include the purpose of the output in your description.

7. Would a series or parallel circuit be needed to turn on the output from question 4? Draw a sketch of a possible circuit.

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Conductor

Power Source

Load (output)

Control

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