Right Hand Rule: Direction of Angular Momentum Vector

In summary, the right hand rule is used to determine the direction of the angular momentum vector. The vector points in the direction of the thumb if the fist is clenched. If the clock is on the wall, the angular momentum vector is perpendicular to the plane of the wall.
  • #1
scar123
11
0

Homework Statement



Clock hands move slowly but they do have a small angular momentum. According to the right hand rule, in which direction, with respect to the clock face, does the angular momentum vector point?


Homework Equations



right hand rule

The Attempt at a Solution


Pointing right?
 
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  • #2
Do you know what the right hand rule is?
 
  • #3
Doc Al said:
Do you know what the right hand rule is?

Yes... you have to curl your fingers, and then the thumb points in the direction of the vector?
I just don't understand this. Could you give me a hint?
 
  • #4
scar123 said:
Yes... you have to curl your fingers, and then the thumb points in the direction of the vector?
That's right. Make a half-closed fist with your right hand but with your thumb sticking straight out. Align your hand until your fingers curl in the direction that the hands are turning (which is clockwise, of course). The direction of your thumb is the direction of the angular momentum vector.
 
  • #5
But your thumb can go in many directions... that doesn't make any sense.
 
  • #6
scar123 said:
But your thumb can go in many directions... that doesn't make any sense.
If you assume your four fingers (excluding the thumb), are sweeping an area in the plane made by the X and Y axis, the thumb will be point in the Z axis. So if there was a clock on your computer screen, the Z axis would be coming out of the screen and into the screen. Now, you have to determine whether the angular momentum is coming perpendicularly out of the plane of the clock and towards you, or in the opposite direction, away from you by seeing which way your four fingers are pointing (They should be moving in a clockwise direction).
 
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  • #7
scar123 said:
But your thumb can go in many directions... that doesn't make any sense.
See a doctor... quick! (Just kidding.) Just make a fist with your thumb pointing up. Like you're making a "thumb's up" gesture.

Here's a picture (look at the right-most hand diagram in the middle): http://www.physics.brocku.ca/faculty/sternin/120/slides/rh-rule.html" [Broken]
 
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  • #8
Ok I made a fist haha. But then it doesn't make sense of how i should allign it with the clock hands lol... Is it just going to point upward? hhaa
 
  • #9
scar123 said:
Ok I made a fist haha. But then it doesn't make sense of how i should allign it with the clock hands lol... Is it just going to point upward? hhaa
Describe your final answer with respect to the clock. You should know that when you use the right hand rule, your thumb direction is perpendicular to the plane of your curled fingers. The clock hands move in the plane of the clock, so the angular momentum vector must be perpendicular to the clock face. You have only two choices. Which must it be?
 
  • #10
north east and north west are my two choices?
 
  • #11
scar123 said:
north east and north west are my two choices?
Specify the direction with respect to the clock. (We don't know which way the clock is pointing, so north and east mean nothing here.)

If the clock is on the wall, then the plane in which the clock hands move is the plane of the wall. The angular momentum vector must be perpendicular to the wall. So what are your choices? (There are only two ways something can point perpendicular to the wall--or the clock face.)

Read Battlecruiser's post--that might help you visualize what's going on.
 

1. What is the right hand rule?

The right hand rule is a method used to determine the direction of a magnetic field, electric current, or force in a three-dimensional space.

2. How is the right hand rule used in physics?

In physics, the right hand rule is used to determine the direction of a magnetic field around a current-carrying wire, the direction of a force on a charged particle moving through a magnetic field, and the direction of a force on a current-carrying wire in a magnetic field.

3. Can you explain the steps of the right hand rule?

The steps of the right hand rule are as follows: 1. Point your right hand in the direction of the current or force. 2. Curl your fingers towards the direction of the magnetic field. 3. Your thumb will point in the direction of the resulting force, magnetic field, or current.

4. Is there a left hand rule as well?

Yes, there is a left hand rule which follows the same principles as the right hand rule, but uses the left hand instead. It is commonly used in situations involving negative charges or electron flow.

5. When is the right hand rule most commonly used?

The right hand rule is most commonly used in electromagnetism, specifically in situations involving electric and magnetic fields and their interactions with charged particles and currents.

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