(a)
What is the minimum speed the spaceship will need for the captain to be no more than 60 years old at arrival in December 2009 the discovery was announced of a planet that may have a large amount of water and hence would be a good candidate for possible life. The planet, GJ 1214b, orbits a small star that is 42 light years from Earth. In the future we might decide to send some astronauts to explore the planet. When they arrive there, we want them to be young enough to perform tests. Suppose that the captain is 25 years old at launch time?
Explanation of Solution
Calculation:
At rest, the half-life of a certain radioisotope is
A 25-year-old captain pilots a spaceship to a planet that is
Conclusion:
Minimum speed the spaceship will need for the captain to be no more than 60 years old at arrival in December 2009 = 0.77c
(b)
How many years after launch from Earth will it be when the signal arrives at Earth as soon as the spaceship arrives at the planet, the captain has orders to send a radio signal to Earth to notify Mission Control that the trip was successful.? You can ignore acceleration times and any motion of Earth and GJ 1214b.
Explanation of Solution
Calculation:
Years after launch from Earth will it be when the signal arrives at Earth as soon as the spaceship arrives at the planet = 97 ly
Conclusion:
Years after launch from Earth will it be when the signal arrives at Earth as soon as the spaceship arrives at the planet = 97 ly
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Chapter 25 Solutions
COLLEGE PHYSICS
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- Is it possible for your parents to be younger than you? Explain how.arrow_forward6. Consider a planet of mass m in orbit about a star of mass M. Since M >> m, we can assume the star is at rest. a) Show that the energy of the planet can be written as GMm E = 2mr? b) Now assume the planet is in a perfectly circular orbit. What is the energy in this case? c) Represent the energy obtained in part (b) on an energy diagram. (Draw and label very carefully.)arrow_forward1. The nearest stars, apart from the Sun, are light-years away from Earth. If we are to investigate these stars, our space ships will have to travel at an appreciable fraction of the speed of light. (a) You are in charge of estimating the energy required to accelerate a 10,000 kg capsule from rest to 10 percent of the speed of light in one year. What is the minimum amount of energy that is required? (b) Compare your estimate to the amount of energy that the United States uses in a year about 5 x 1020 ). (c) Estimate the minimum average power required of the propulsion system. ((a) 4.5 x 1018 J, (b) 0.9%, (c) 1.4 x 1011 W)arrow_forward
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