24. On p. 15 we did an example with a shipment of space medicine. Re-do this problem, beginning by converting all the units to meters and seconds. You should end up with the same answer as we did (the medicine ages 1.45 days). But you should also be convinced that relativistic units are a good time- saver! Example: Time Dilation A space station needs to send relief medicine to a planet 3 light-days away. (A light-day is the distance light can travel in a day.) Their fastest ship can go at 0.9c, but the medicine only lasts 2 days before expiring. Will the medicine reach the planet in time? Answer: We can write the speed of the rocket as 0.9 light-days/day, so it takes the rocket t=d/v = 3.333 days to reach the planet. (As a sanity check, note that at the speed of light it would take 3 days, so at a slightly lower speed it must take slightly longer.) The situation may look hopeless, but remember that the rocket clock is moving slowly by a factor y = 1/1 - 0.9 = 2.294. So while the planet frame says 3.333 days pass, the rocket clock only ticks off 3.333 days/2.294 = 1.45 days. The medicine ages less than 1.5 days on the journey and the planet is saved.