PURPOSE:
To expose the student to new equipment and lab procedures. And to calculate the acceleration of a falling object in the laboratory.

INTRODUCTION:
Acceleration is a vector quantity which is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity. Sometimes an accelerating object will change its velocity by the same amount each second. This is referred to as a constant acceleration since the velocity is changing by a constant amount each second. An object with a constant acceleration should not be confused with an object with a constant velocity. Don't be fooled! If an object is changing its velocity -whether by a constant amount or a varying amount - then it is an accelerating object. And an object with a constant velocity is not accelerating.

Gravity pulls objects toward the earth at a constant acceleration of 9.8 m/s². That means that the velocity of a falling object is changing at a constant rate. If we know that change in velocity over a period of time we can calculate the acceleration using:

a = (v_f - v_o)/t

where v_f is the final velocity, v_o is the initial velocity during the period of t, time. The SI units are m/s² resulting from the fact that velocity (m/s) is divided by time (s). During this lab you will measure the distance that an object drops during several consecutive periods of time, 0.1 seconds. You will then calculate the velocity during each of these time periods and from that calculate acceleration.

A battery operated device will hold a spool of thin electro-sensitive paper. An object is attached to the end of this paper by a clamp on the object. A magnetic set of jaws on the device prevents the object and tape from falling. When a release button is pressed, a sparker starts to place marks on the tape every 0.1 seconds and the tape is released

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A 1 kg, 500 g and 100 g mass brass weight will serve as the falling object. A clamp is attached to the top of each mass.

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A tape measure graduated in cm is provided to determine the distance between marks on the paper tape.

 

If you get into trouble and perform some procedure that causes the lab to fail(lab equipment will no longer operate), you can press the "Reset" button and the simulation will return to the starting position.

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PROCEDURE:

1) You can adjust the background shading by clicking on the "Special" button to the right and selecting "Background". Click on the "Special" button and select "Print Blank Report" to obtain a web page that can be printed and used as a lab report. (the program will not be interrupted)

2) Located at the end of the upper shelf is a special device. This device has a roll of paper tape positioned above it. This tape can unwind and flow out with very little friction when a falling object is attached to it. Near the top a set of jaws holds the paper tape until the device's release button is pressed. Near the bottom of the device a blue box contains a spark generator. When turned on a spark will jump across the small slit where the paper tape hangs through. This paper tape is treated with a substance that leaves a black spot if a spark comes in contact with it. So, if an object is hung from the paper tape and the release button is pressed, the tape will flow past the sparker and the sparker will leave black marks. The sparker is set to generate a spark every 0.10 seconds.

3) Pick up the 1 Kg brass weight and hold its top clamp on the bottom end of the white paper tape hanging from the device on the shelf. When released it should attach to the tape and hang in the air. Remember that the jaws of the device is holding the tape. Click on the red On/Off button on the device. You should hear the sparker start while the brass weight and paper fall to the table. Turn the device off.

4) Notice that the sparker has left a trail of black dots on the paper. Pick up the tape measure on the table and hold it next to the paper tape. Click on the black button on the tape measure and then drag the tape measure container. Notice how the tape will extend outward. Clicking again on the tape measure button will lock that position of the measuring tape. Position the tape measure so that the bottom edge is lined up with the bottom dot on the paper tape.

5) Record the distance from dot 1 to dot 2, dot 2 to dot 3, dot 3 to dot 4 and finally dot 4 to dot 5.

6) Press reset and repeat this lab with a different mass (your choice) and record the distances.

7) Calculate the requested values asked for on the lab sheet and any given by your teacher. For help on these values click on the "Special" button and select "View Data & Hints". Select "File Report" to send a copy to be viewed by your teacher.