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

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Homework Help Overview

The problem involves determining the displacement vector of the tip of a clock's minute hand at specified times, focusing on its length and angular position. The subject area relates to kinematics and vector analysis.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the initial setup of the problem, including the drawing of a diagram and the definition of axes. There is an exploration of the angle made by the minute hand at different times and the calculation of displacement based on these angles. Some participants question the correctness of the displacement calculations and the geometric interpretation of the triangle formed by the minute hand's position.

Discussion Status

The discussion is ongoing, with participants raising questions about the accuracy of the calculations and the geometric representation of the problem. There is a focus on breaking down the components of the vectors involved, and some guidance is offered regarding the interpretation of the angles and sides of the triangle.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is an emphasis on ensuring that any approach taken leads to the correct interpretation of the displacement vector.

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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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