What Is the Displacement Vector of a Clock's Minute Hand at Different Times?

AI Thread Summary
The discussion focuses on calculating the displacement vector of a clock's minute hand at specific times. For the time interval from 8:00 to 8:20 A.M., the minute hand's displacement is determined to be 8 cm at a 30° angle below the horizontal. In contrast, from 8:00 to 9:00 A.M., the displacement is zero since the minute hand returns to its original position. The participants discuss the geometry involved, including breaking down the triangle formed by the minute hand's movement into components. Overall, the calculations and geometric interpretations are central to understanding the displacement vectors.
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Homework Statement


The minute hand on a watch is 2.0 cm in length. What is the displacement vector of the tip of the minute hand:
a) From 8:00 to 8:20 A.M.?
b) From 8:00 to 9:00 A.M.?


Homework Equations


N/A.


The Attempt at a Solution


So, first I drew a diagram of the clock and its initial position. Assuming 3:00 and 9:00 to be the x-axis, and 12:00 and 6:00 to be the Y-axis, and that 6:00 makes a 90° with 3:00, then when the minute hand points to 4:00 (denoting 8:20), it's angle, theta, would then make an angle of 30° with the negative x-axis. So, the displacement of the minute hand would then be:
\vec{d} = 4 * 2.0 cm = 8 cm [30° below the horizontal]
Is this correct?

As for b, the displacement is equal to 0, since the minute hand ends up exactly where it started after a change in distance from 8:00 to 9:00 A.M., correct?
 
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Retribution said:
So, the displacement of the minute hand would then be:
\vec{d} = 4 * 2.0 cm = 8 cm
Is this correct?

So you have a triangle with two sides of 2 cm, and the third side of 8 cm?

Can you draw that?
 
NascentOxygen said:
So you have a triangle with two sides of 2 cm, and the third side of 8 cm?

Can you draw that?
So, now I would need break the 2 cm side that makes an angle of 30 degrees with the negative x-axis into components, correct?
 
Retribution said:
So, now I would need break the 2 cm side that makes an angle of 30 degrees with the negative x-axis into components, correct?

At 20 mins past, the hand makes an angle with the positive x-axis.

Any method that gets the right answer is okay. I broke the triangle up into two equal triangles.
 
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