Twin A makes a one way trip at 0.6c to a star 12 light years away while twin B stays on Earth. Each twin sends the other a signal once a year by his own time. (a) How many signals does A send during the trip

8 signals received by twin A during the trip.

Explanation:

Given that,

Distance = 12 light year

Speed = 0.6 c

Time = 1 year

We need to calculate the time by A

Using formula of time

Put the value into the formula

Similarly,

The expression for distance cover by A

We need to calculate the time

Using formula of time

We need to calculate the signals received by twin A

Using formula for number of signals

Put the value into the formula

Hence, 8 signals received by twin A during the trip.