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Future space rockets might propel themselves by firing laser beams, rather than exhaust gases, out the back. The acceleration would be small
Question
Future space rockets might propel themselves by firing laser beams, rather than exhaust gases, out the back. The acceleration would be small, but it could continue for months or years in the vacuum of space. Consider a 1200 kg uncrewed space probe powered by a 15 MW laser. After one year, how far will it have traveled and how fast will it be going
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Physics
5 years
2021-08-18T05:38:29+00:00
2021-08-18T05:38:29+00:00 1 Answers
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Answers ( )
Answer:
Acceleration = 0.0282 m/s^2
Distance = 13.98 * 10^12 m
Explanation:
we will apply the energy theorem
work done = ΔK.E ( change in Kinetic energy ) —- ( 1 )
where :
work done = p * t
= 15 * 10^6 watts * ( 1 year ) = 473040000 * 10^6 J
( note : convert 1 year to seconds )
and ΔK.E = 1/2 mVf^2 given ; m = 1200 kg and initial V = 0
back to equation 1
473040000 * 10^6 = 1/2 mv^2
Vf^2 = 2(473040000 * 10^6 ) / 1200
∴ Vf = 887918.92 m/s
i) Determine how fast the rocket is ( acceleration of the rocket )
a = Vf / t
= 887918.92 / ( 1 year )
= 0.0282 m/s^2
ii) determine distance travelled by rocket
Vf^2 – Vi^2 = 2as
Vi = 0
hence ; Vf^2 = 2as
s ( distance ) = Vf^2 / ( 2a )
= ( 887918.92 )^2 / ( 2 * 0.0282 )
= 13.98 * 10^12 m