Question

n11. A spaceship is moving away from an asteroid with a speed of 0.80c relative to the aster- oid. The spaceship then fires a missile with a speed of 0.50c relative to the spaceship. What is the speed of the missile measured bv astronauts on the asteroid if the missile is fired on e lozt Choose one: a) 0.30c 50c c) 0.93c Cr messle e) 0.65c 2 2 2.0

Answer 1

If a particular coordinate is moving with a velocity u'_x and a particle moves in that x' frame with a velocity ( say suppose v). Then taking these two points let's say an observer who is at rest will see the velocity ( relative velocity) in the form of equation

V_relative =( u_x' + v) /( 1+ { u_x'. v }/c²⁾

So here spaceship --> as the moving coordinate.

The Missile fired --> the particle moving with velocity v.

Since they are moving in the same direction so we have u_x' = 0.8c and v = 0.5c

Now relative velocity = ( 0.8 c + 0.5c) /( 1 + 0.8*0.5 c2/c2)

= 1.3c/1.4

= 0.928c = approximately 0.93c Answer (c)

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