- #1
Gavandeshaq
- 18
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Homework Statement
A laser is used to focus 25 MW of light onto a missile for 15 seconds. If the mass of the missile is 200 kg, determine the speed change imparted to the missile in the direction of the laser beam.
Homework Equations
E=hf
p=h/[itex]\lambda[/itex]
F=dp/dt
[itex]\lambda[/itex]f=c
F=ma
The Attempt at a Solution
I figured I'd try and get the power into joules, so that I could find the frequency, and henceforth the wavelength etc.
I found that the laser transfers 1.6x10^7 J across the 15s, when putting this into E=hf I came out with a frequency of 2.4x10^40 Hz (Seems fairly large, but since I know very little about lasers, I'm going with it).
Now I must be missing something here, cos I can't see what other variables I'm able to figure out from here, or even if I've done the steps so far correctly.
This isn't a homework question as such, it's from a past university paper and I'm revising for my resits. I could really use help on this ASAP, cos I'm worrying that I might not pass my resits...