Name____________________________________Date____________

# Lab: Pulleys and Inclined Planes

Materials Needed: Pully, Weights, Meter Stick or Ruler, Spring Scale, Ring Stand (or use table to hold pulley)

## If You Need to Move a Piano......

Mr. Smithers has hired a moving company to deliver a piano to the second floor office. As an employee of this company, you are charged with the task of designing a method of piano moving. Recalling high school physics, you know that machines can help you do WORK. You suggest two machines to help you move the piano. Describe (or sketch) how each of these machines could be used to get the piano up to the second floor office. Fortunately, there is a window wide enough to get the piano inside.

Proposed Designs (sketch or describe)

Option 1: Inclined Plane

Option 2: Pulley

To determine which option is the best option, you need to test your design and determine which machine has the greater efficience. To do this, you will make a MODEL of the design using a weight to represent the piano.

## Pulley System

Attach a weight and a spring scale to the pulley system as shown below. You will test 3 weights in order to deterimine the EFFICIENCY of your machine.

 WORK OUT WORK IN Weight (in Newtons) mass x 9.8 m/s2 Distance Weight Raised (height) Work Done (in Joules) W = Fd Force (read on spring scale) Distance You pulled Work Done (in Joules) W = Fd EFFICIENCY Average Efficiency :

## Inclined Plane

In order to compare, choose one of your trials from the pulley experiment above. You will be raising the same weight to the same height.

 WORK OUT WORK IN Weight (in Newtons) mass x 9.8 m/s2 Distance Weight Raised (height) Work Done (in Joules) W = Fd Force (read on spring scale) Distance You pulled (length of ramp) Work Done (in Joules) W = Fd EFFICIENCY

Also, for an inclined plane, calculate the ideal mechanical advantage of your system;

# = ______

## Analysis

1. Based on your tests, which system (pulley or inclined plane) has the greatest efficiency? ________________

2. Supposing you choose to use an inclined plane to move the piano into the building. Suppose your team suggests that you use a shorter ramp. Compare the two designs below, which one will require you (and your team) to do the least amount of work (work out)?

3. Which of the designs above has the greater mechanical advantage. Show calculations based on the following data:

Height to 2nd story window = 20 m
Length of Ramp in design A = 80 m
Length of Ramp in design B = 40 m

IMA of Design A = ____________ IMA of Design B = ______________

4. Calculate the work necessary to move the piano in Design A if it is pushed with a force of 80 Newtons across the length of th 80 meter ramp
(this is your WORK IN) *Show Work*

In the same scenario, the piano weighs 2,600 Newtons and you have moved it vertically to the 2nd story window, a distance of 20 meters. What work is done to lift the 2,600 N piano a distance of 20 m (this is your WORK OUT) *Show Work*

5. What is the EFFICIENCY of your Design A? _________
*Show Work*