Rocket A passes Earth at a speed of 0.79 c . At the same time, rocket B passes E

ID: 1605630 • Letter: R

Question

Rocket A passes Earth at a speed of 0.79 c. At the same time, rocket B passes Earth moving 0.86 crelative to Earth in the same direction as A.

Part A

How fast is B moving relative to A when it passes A?

Express your answer using two significant figures.

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Rocket A passes Earth at a speed of 0.79 c. At the same time, rocket B passes Earth moving 0.86 crelative to Earth in the same direction as A.

Part A

How fast is B moving relative to A when it passes A?

Express your answer using two significant figures.

v = c

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Speed of rocket B relative to earth will be given by:

V = (v+u)/(1 + vu/c^2)

where v = speed of rocket A relative to earth

u = speed of rocket B relative to rocket A

using the given values:

0.86*c = (0.79*c + u)/(1 + 0.79*c*u/c^2)

0.86*c = (0.79*c + u)/(1 + 0.79*u/c)

solving the equation

0.86*c + 0.86*0.79*u = 0.79*c + u

u = 0.07*c/(1 - 0.86*0.79)

u = 0.218c

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