Simple Machines: The Inclined Plane Lab



Simple Machines: The Inclined Plane Lab

Introduction:

A simple machine can be used to make work easier. This doesn’t mean that you can get by with less work. If fact, you always will have to do more work when you use a simple machine than if you don’t use one!

Remember: a simple machine reduces the force you have to use; it does not reduce the amount of work you must do. With simple machines we are able to reduce the force that must be used by exerting that force through a larger distance. When the force is less we say the job is “easier.”

You have learned that scientists describe the helpfulness of simple machines in terms of Mechanical Advantage. A machine’s mechanical advantage is the number of times the machine multiplies force. (It compares the input force with the output force) For example, imagine that you had to push a 500 N weight up a ramp and only needed to push with 50 N of force the entire time. The mechanical advantage would be the output force (500 N) divided by the input force (50 N) for a mechanical advantage of 10. A machine that has a mechanical advantage that is greater than 1 can help move or lift heavy objects because the output force is greater than the input force.

There are two types of mechanical advantage. An Ideal Mechanical Advantage (if everything worked perfectly) and the Actual Mechanical Advantage (the mechanical advantage you actually get).

People also tend to be interested in the efficiency of the simple machines they use. Efficiency compares how much work goes into a simple machine with how much work comes out.

In this lab you will be finding the mechanical advantage and efficiency of an inclined plane. You will see if changing the angle (by changing the height) of the inclined plane or adding mass to the resistance will change any of these.

Remember to record all data and answer all questions on the lab write-up.

Purpose: In your own words, state the purpose of this lab.

Lab Formulas:

| |

|Work = Force X Distance |

| |

|Distance In (length of ramp) Force Out (weight of cart) |

|IMA = ------------------------------------- AMA = ------------------------------------- |

|Distance Out (height of ramp) Force In (effort force) |

| |

| |

|Work Out |

|Efficiency (in %) = ------------------- X 100 |

|Work In |

Lab Materials:

Inclined plane 2 ring stands ring stand clamp

Cart meter stick 5 N & 10 N spring scale

Procedure:

1) Set up the inclined plane so the height of the ramp is 30 centimeters. (I recorded the height on the lab write-up for you).

2) Measure the length of the ramp (inclined plane) in meters; record.

3) Attach one end of the string to the cart and the other end to the spring scale.

4) Measure the weight of the cart.

5) Pulling parallel (along the ramp angle), pull the cart up the ramp at a constant speed with the spring scale. Record the effort force needed.

Calculations: Use the formula to calculate the work done in lifting the cart 30 cm without the ramp. (That will be the “Work Out” in your calculations.) Then calculate the ideal mechanical advantage (IMA), actual mechanical advantage (AMA), the work required to raise the cart (“Work In”), and the efficiency of the ramp.

Predictions:

1) Will the ideal mechanical advantage increase, decrease, or remain the same if you make the inclined plane steeper?

2) Will the efficiency increase, decrease, or remain the same if you make the inclined plane steeper?

6) Now, raise the ramp height to 45 centimeters and fill in the data table for that height.

Analysis and Conclusions: Answer the questions on the lab write-up.

Note, This lab was adapted from the James Madison Memorial High School ISP and your textbook.

Simple Machines: The Inclined Plane Lab Name: _________________

Purpose: ________________________________________________________________

________________________________________________________________

Lab Materials:

Predictions:

1) Will the ideal mechanical advantage increase, decrease, or remain the same if you make the inclined plane steeper? ____________________________________

2) Will the efficiency increase, decrease, or remain the same if you make the inclined plane steeper? _____________________________

Data:

| |Ramp (30 cm height) |Ramp (45 cm height) |

|Height |.3 m |.45 m |

|Length | | |

|Weight of cart | | |

|Effort force | | |

| | | |

|Work (no ramp) = Work Out | | |

|IMA | | |

|AMA | | |

|Work In | | |

|Efficiency | | |

Lab Formulas:

Simplified Procedure:

Analysis and Conclusions:

1) How does a ramp (inclined plane) make a job easier? ___________________________

______________________________________________________________________

2) Does it require more or less force to lift the cart using the ramp?___________________

3) Is more or less work done in lifting the cart using the ramp? _____________________

4) How does the ideal compare with the actual mechanical advantage?________________

______________________________________________________________________

5) What force causes a difference between the ideal and actual mechanical advantage?

______________________________________________________________________

How could this force be reduced?___________________________________________

6) Which is easier (requires less force): using a short, inclined plane or using a long not-so-steep inclined plane? ________________________________________________

7) Which requires less work: using a short, inclined plane or using a long not-so-steep inclined plane? _______________________________________________________

8) List the six types of simple machines:

____________________ _____________________ ____________________

____________________ _____________________ ____________________

Simple Machines: Levers Lab

Introduction:

Simple Machines do not let you get away with doing less work. You must do exactly as much work, plus a little more to overcome friction.

The advantage of the simple machine is that it makes the task easier because the machine reduces the force required or changes the direction in which the force is applied. A simple machine may make a task easier, but they always require more work IN than you can get back OUT.

All machines are made up of one or more simple machines. Levers are simple machines that change the amount of force needed to lift objects and can change the direction in which the lifting force is applied. For example, an object can be lifted upward by pulling downward. You have experience with this effect on the playground. If your friend is sitting on the far end of the teeter-totter and you want to get on, you pull downward in order to lift them up off the ground.

Levers can be divided into three groups or “classes” depending upon the relative position of three points on the lever...these three points are the fulcrum, the effort force, and the resistance force.

The Fulcrum - is the fixed point of the lever, the pivot point.

The Effort - is the place on the lever where you are applying your force - pushing or pulling. It is the place where you are putting your work IN to the lever. It is the force which we must apply to accomplish the task using the simple machine.

The Resistance - is the place on the lever where the object which we want to move is located. It is the place where the work that comes OUT of the machine is accomplished. It is the force which must be overcome in order to accomplish the task without using the simple machine.

In this lab you will become familiar with the three classes of levers and be able to identify how the use of a lever changes the nature of the work.

In other words, the ADVANTAGE that can be gained by using a lever.

Part 1: Identifying the class of a lever

Look at the diagrams of the three classes of levers below. Use your textbook, pages 106 & 107 to help you place a check on the lines in the boxes.

FIRST CLASS LEVERS:

The fulcrum is always located between the effort and resistance forces.

|[pic] | |

| |What is possible… |

| |Gain In... Loss In... |

| |____ Force ____ |

| |____ Distance ____ |

SECOND CLASS LEVERS:

The resistance force is always located between the fulcrum and the effort force.

|[pic] | |

| |What is possible… |

| |Gain In... Loss In... |

| |____ Force ____ |

| |____ Distance ____ |

THIRD CLASS LEVERS:

The effort force is always located between the fulcrum and the resistance force.

|[pic] | |

| |What is possible… |

| |Gain In... Loss In... |

| |____ Force ____ |

| |____ Distance ____ |

If we were to summarize the positions of the three points on the lever, we would find that each class of lever always has the same point located between the other two points.

First Class Lever... (F)ulcrum

Second Class Lever... (R)esistance force

Third Class Lever... (E)ffort force

Can you see that the three classes of levers are always F-R-E (free) for the taking?

Procedure:

Part 2: The operation of a first class lever

1) Use a meter stick, clamp, and hangers to assemble a first class lever. The fulcrum should be located at the 50 cm mark.

2) Hang a 500 gram resistance mass at the 80 cm mark. Note that mass is not equal to a force, however it is proportional to the force called weight. Using Newton's 2nd Law formula (F=ma), the 500g mass weighs 4.9 N. This is the resistance force. I filled it in for you on the lab report.

3) Hang a spring scale upside down at the 20 cm mark.

4) Will this setup let you apply less force than the resistance? Predict the Mechanical Advantage on the lab report. Choose >1, 1, 1, 1, ................
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