## Physics Assignment Help

PHYS 150 NAME:

Hybrid Assignment: Airplane on a String

Due Date: Thursday, Feb. 25, 2016, at the beginning of class

You may answer all questions (and show calculations) on separate notebook pages and hand them in. You do not need to hand in this

worksheet.

Open a web browser, and navigate to the following web page:

Look for the video called “Airplane on a String.” Click the DMV Player link under the image for the video.

When the video loads, you should see a scene as shown in Figure 1:

Figure 1: Screenshot using DMV player

Play the video in its entirety. The toy airplane is moving like a conical pendulum, just as our “flying pig” did in

class. The toy airplane moves in a circle at a steady speed. That circle is in a horizontal plane.

The on-screen protractor can be used to measure the angle between the string and the vertical, but only when the

plane is facing us directly, or facing directly away from us. You may need to play the video a couple of times

to determine exactly when that happens (pause it near each of those locations, and use the forward/backward

frame advance buttons).

1. Find the frame where the airplane first faces directly away from us, on the left side of the screen.

(a.) What is the frame number at this instant:

(b.) What is the angle between the string and the vertical (to the nearest degree):

(c.) What is the tension in the string at that instant (to the nearest 0.5 N):

2. Find the frame where the airplane first faces directly toward us, on the right side of the screen.

(a.) What is the frame number at this instant:

(b.) What is the angle between the string and the vertical (to the nearest degree):

(c.) What is the tension in the string at that instant (to the nearest 0.5 N):

3. Quick check: Your answers to 1 (b.) and 2 (b.) should be the same (or very close). Also, your answers to

1 (c.) and 2 (c.) should be the same (or very close). Briefly explain why:

4. How many seconds does it take for the toy airplane to move through 1⁄2 revolution (half-circle)? (Use your

answers to 1 (a.) and 2 (a.).

5. What is the angular speed of the toy airplane in radians per second? (See text, Ch. 5)

6. When the toy airplane is facing us on the right side of the screen (as described in 2), draw a free-body

diagram for the airplane. Label each force as “Force on plane by ____.” Let the positive-x direction point

inward toward the center of the circle. Let the positive-y direction point vertically upward.

7. Use Newton’s Second Law, along with the angle and string tension information from 2 to calculate the mass

of the toy airplane. Show all of your steps. (This will require trigonometry, algebraic substitution, etc.)

8. Now use your results, along with our knowledge of uniform circular motion and radial acceleration (Ch. 5),

to calculate the radius of the horizontal circle in which the airplane is moving.

9. How do you know by observing the toy airplane that it is accelerating? (Just use our basic understanding of

acceleration.)

1.

a)153 frames

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