# Recent content by Beaker87

1. ### Want to become a teacher, where to start?

If you served for 6 or more years, see the following: http://www.kyepsb.net/certification/veterancert.asp Otherwise, find what most fits you here: http://www.kyepsb.net/certification/certaltroutes.asp Since Physics teachers are in very high demand, it is likely that you can get in through an...
2. ### Very hard mechanics question

You need to set up equations for each of the following: 1. The projectile motion problem that starts when the string is no longer taught. 2. The position (angle) at which the ball enters projectile motion (when the gravitational force inward surpasses the necessary centripetal force). 3. The...
3. ### [Help] Grade 12 University Prep Physics Design Project

Consider that a string could be used as a timing mechanism; as the propeller spins, the string gets pulled tighter (as it wraps around the axle.) Another idea is a very well lubricated nut timing mechanism. Place a nut on the (threaded) axle, and don't allow it (the nut) to rotate. As the axle...
4. ### Weight of ball/water/cylinder system as the ball falls

Try to think in terms of force acting on the ball. The ball is moving downward, and then when it hits the water, what happens? The ball is moving downward in the water, and then when it strikes the bottom, what happens?
5. ### Electromagnetism/Magnetism concept questions.

The formula for finding the magnetic force between two magnets can be found here: http://en.wikipedia.org/wiki/Magnet#Calculating_the_magnetic_force
6. ### Problem with relativistic doppler?

Wikipedia is starting in the reference frame of the source of the waves in order to find the time between successive crests hitting the moving observer in the reference frame of the source. Then Wikipedia uses this time in the time dilation equation in the observer's reference frame in order...
7. ### Angular velocity and acceleration for catapult arm

Do not solve for the left side of the catapult arm separately from the right. Once you have the moment of inertia for the whole arm, use that to find the angular velocity of the whole arm. As for the energy equation you have written, at the beginning, the catapult only has spring potential...
8. ### Electromagnetism/Magnetism concept questions.

I was thinking that Unillusive could use the equations for the interaction between charged particles, and discuss any similarities to the equation for the interaction between magnets. I.e. the inverse square relationship, and as you said, the fact that like charges attract, while unlike...
9. ### Electromagnetism/Magnetism concept questions.

Good, this is correct. You may, however, want to reference the following formula in your explanation: \stackrel{\rightarrow}{F}=\stackrel{\rightarrow}{I}L\times\stackrel{\rightarrow}{B} Here you are supposed to be comparing the electric force between two charged particles to the magnetic...
10. ### Angular velocity and acceleration for catapult arm

I would recommend against force dynamics. I think the problem would be much easier for you to solve using energy dynamics. The formula you would use to do this is: KE_{arm}=\frac{1}{2}I\omega^2 Now, this next thing is important: Are you throwing the projectile with a sling, or is it...
11. ### Max height of weighted spring

Try to set the potential energy at the bottom (where the ball is released) to the potential energy at the very top.
12. ### Direction of Force (Motor Effect)

The current in the second picture appears to be flowing diagonally down and to the right.
13. ### Volume of a cone using integrals

Draw the cone on your paper as a triangle facing down. Pick some point along the center axis. The radius is the distance from the center to the edge, and the height is the distance from the bottom to the current location. Now you can use trigonometry to solve for the radius in terms of the...
14. ### Waves on an antenna problem

If it is fixed at one end and free at the other, one end must be a node, and the other end must be an antinode. Try to draw what the acceptable standing waves would look like; that will help you to find their wavelengths.
15. ### Water level in tank

Don't think of the start of this problem, think of the problem when the tank is at equilibrium. If the tank is to be in equilibrium, the velocity of water entering times the cross sectional area of the entranceway is equal to the velocity of water leaving times the cross sectional area of the...