Question 1.)

A sphere with emissivity 0.653 and radius of 0.791 m has a temperature of 57.4C. If the sphere is placed inside an environment at temperature 80.7C, what is the net rate of energy exchange? Calculate the power of absorption and subtract the power of radiation to give the net power. Use Watts (W) as your unit and give the unit.

Question 2.)

A new particle known as Jamesparticle is discovered, and measured in a laboratory to have an average lifetime of 3 s before undergoing a radioactive decay. If a stream of highly energetic Jamesparticles are measured to have a mean lifetime of 15.9 s, how fast are the Jamesparticles moving relative to the Earth (where the measurements are occurring)? Put your answer as a ratio of the velocity relative to the speed of light, v/c.

Question 3.)

A high speed particle enters a medium and travels 8.6 mm before it decays. If the particle was travelling at 0.98c relative to the medium, what would the proper lifetime of the particle be? Give your answer in picoseconds (10^-12s) and don't give units.

Question 4.)

The SS-Brown, an intergalactic transport vessel, travels at a speed of 0.97c relative to the Earth, to a distant planet in a galaxy far far away. The crew of the ship hibernate for 1 year during the trip. Relative to the Earth, how long were the crew asleep for? Put your answer in years and don't give units.

Question 5.)

Justin is on a spaceship travelling at 0.998c. Onboard the ship is a table of length 1.6 m, with the length inline with the direction of travel of the ship. What is the length of the table as measured by Justin on the ship?