Helpmyphysics

How potential and kinetic energies relate with friction in a skateboard park.

Here is projectile video number one looking at projectiles aimed at walls.

By working out the horizontal and vertical components then using the horizontal component to determine the time it takes to reach the wall, the displacement S can be found.

A quick video to calculate the acceleration down a slope.

For Higher Physics students:

• Determine the period and frequency of the ac supply
• Find the rms voltage of the ac signal

Click the above picture to take you to your momentum lab.

A capacitor can be used in a sensor circuit to switch on a transistor after a time interval.
Such a voltage divider circuit will act as a kind of timer.
The time the voltage across the capacitor reaches 0.7 v, to switch on the transistor, can be short or long depending on the size of the capacitance of the capacitor or the size of the resistor its being charged through.

To lengthen the time interval the resistance can be made bigger or the vakue of the capacitor’s capacitance can be made bigger.

Click the picture to go to the sim.

Some questions:

1. What do you notice about the variable resistor’s voltage as its resistance increases?
2. What do you notice about the sum of the voltages across the resistors?
3. For each resistor in turn, take the ratio of voltage across it and divide by the resistance. What do you notice?