How does a guitar string make a sound wave? a. striking the string compresses the air around it to create a sound wave. b. the vibrating string alternately compresses and rarefies the air to make sound. c. the string strikes the wood of the guitar, which vibrates to make the sound. d. the string moves air through the hole in the guitar to create sound. **i am not sure : (

Acharge of 8.4x10^-4 c moves at an angle of 35 degrees to a magnetic field that has a field strength of 6.7x10^-3 t. if the magnetic force is 3.5 x10 ^-2 n, how fast is the charge moving?

Unpolarized light of intensity i_0=750w/m^2 is incident upon two polarizers. after passing through both polarizers the intensity is i_2=280w/m^2. (a) what is the intensity of the light after it passes through the first polarizer in w/m^2? (b) write an equation for the angle between the polarizers in terms of the initial (i_0) and final (i_2) intensities. (c) find the angle between the polarizers in degrees.

If a tank filled with water contains a block and the height of the water above point a within the block is 0.8 meter, what is the pressure at point a?