- #1
UMDstudent
- 33
- 0
Homework Statement
A small homemade firework goes off 3 meters about the surface of the water where a person is diving. The diver is 10 meters below the surface of the water.
(a). How much time passes from the instant the firework goes off until the diver sees it?
(b). How much time passes from the instant the firework goes off until the diver hears it?
When the firework goes off, another individual is traveling on a boat moving at a speed of
30 km per hour away from the firework. That person is standing on the upper deck of the
boat, also 3 m above the surface.
(c). If the person on the boat hears a sound with frequency 200 Hz, what is the actual
frequency of the firework’s sound?
(d). If the frequency of the light emitted by the fireworks is 5 × 10^14 Hz, what is the
wavelength of this light as seen by the diver?
Homework Equations
Formula A : Velocity = Wavelength (gamma) * Frequency ( we can change this around too)
Formula B : Frequency (receding sound) = (1- V(not)/V)*F(not)
The Attempt at a Solution
For beginners, I have no idea how to successfully start, or complete A. & B. (need help)
I however completed C & D and I'm hoping I completed them correctly :
For part C : We use Formula B and here's my setup for this:
(1 - (3.6*10^6(m/s))/(343(m/s)))*200hz = -2.1*10^6 hz
^^Seems very high but i had to convert the speed of the boat from 30 Kilometers per hour to meters per second.
For Part D : We use Formula A and here's my setup :
Wavelength (gamma) = Velocity / Frequency : 3 * 10^8 (speed of light) / 5*10^14 (hz) = 6 * 10^-7 .
^^Very small wavelength. I have no way of checking my answers so I ask please review this and give the best advice. As always, thank you for reviewing my work and hopefully i will get some much needed help with parts A & B.
Very Respectfully,
UMDstudent