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**1. Homework Statement**

An enemy spaceship moves past the earth with a speed of 0.8 c. The captain orders the spaceship weapons department to blast the earth with pulsed laser photons every 10 seconds. For the observers on earth who see the flashes, what is the time interval they measure between photon pulses?

**2. Homework Equations**

[tex]\Delta T = \gamma \Delta T_0[/tex]

**3. The Attempt at a Solution**

Since spaceship is moving,

[tex]\Delta T_0 = 10s[/tex]

[tex] v = 0.8c[/tex]

subbing in the values into the formula we get :

[tex]\Delta T = 16.7s[/tex]

Is this correct?

Another Qns :

for the formula [tex]\Delta T = \gamma \Delta T_0[/tex]

As a guide line, is [tex]\Delta T > \Delta T_0[/tex] for all cases?

Also, does the [tex]\Delta T_0[/tex] mean the duration in which the event happen in the frame of the event. Which in this case is the 10s.

Any help will be appreciated