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

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SUMMARY

The displacement vector of a clock's minute hand, which is 2.0 cm in length, can be calculated for specific time intervals. From 8:00 to 8:20 A.M., the minute hand moves to the 4:00 position, resulting in a displacement vector of 8 cm at an angle of 30° below the horizontal. Conversely, from 8:00 to 9:00 A.M., the minute hand returns to its original position, yielding a total displacement of 0 cm. The calculations involve breaking down the movement into components based on the geometry of the clock face.

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  • Understanding of vector displacement
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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.
 
Last edited:

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