q123.htm

Question #123

Here is a follow-up question to Question #119.

A mass M on a level air track is connected by a string passing over a pulley to a much smaller mass m<<M, as seen in the photograph at the left below.

Releasing M allows m to accelerate it along the air track. The timer measures the time taken for a flag on the top of the air track glider to travel from photocell gate "A" to gate "B," which turns out to be exactly 2.00 seconds. See a video of the action by clicking your mouse on the photograph at the left above.

We have two small problems for you this week.

Part 1:

Suppose that the same experiment is performed with distance D being decreased to D/2, as seen in the photograph at the center above. How long will the glider take to travel from photocell gate "A" to gate "B"?

The time taken for mass m to accelerate mass M a distance D/2 from A to B will be:

(a) 4 seconds.
(b) 2.83 seconds
(c) 2 seconds (the same).
(d) 1.41 seconds.
(e) 1 second.

Part 2:

Now suppose that the same experiment is performed with mass m being increased to 2m, as seen in the photograph at the right above. How long will the glider take to travel from photocell gate "A" to gate "B"?

The time taken for mass 2m to accelerate mass M a distance of D from A to B will be:

(a) 4 seconds.
(b) 2.83 seconds
(c) 2 seconds (the same).
(d) 1.41 seconds.
(e) 1 second.

Click here for Answer #123 after October 7, 2002.

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For questions and comments regarding the Question of the Week contact Dr. Richard E. Berg by e-mail or using phone number or regular mail address given on the Lecture-Demonstration Home Page.