4. You have a twin that stays at home on the Earth while you travel in a spaceship. You leave Earth when you and your twin are both 20.0 years old. You travel from Earth in a straight line at a constant speed for 2.50 years in your frame and you return to Earth in a straight line at the same speed, so that your total travel time in your frame is 5.00 years (assume that the acceleration times are zero). When you return to Earth, you are 12.0 years younger than your twin (biological age). a. What is your twins age when you return to Earth? b. What is the speed parameter of your spaceship for this trip, ß = v/ c ? c. How far from Earth (as measured in the Earth frame) did you travel before turning around (give the answer in light years (ly ) in the Earth frame - hint the speed parameter tells you the speed in units of light years per year)?

4. You have a twin that stays at home on the Earth while you travel in a spaceship. You leave Earth when you and your twin are both 20.0 years old. You travel from Earth in a straight line at a constant speed for 2.50 years in your frame and you return to Earth in a straight line at the same speed, so that your total travel time in your frame is 5.00 years (assume that the acceleration times are zero). When you return to Earth, you are 12.0 years younger than your twin (biological age). a. What is your twins age when you return to Earth? b. What is the speed parameter of your spaceship for this trip, ß = v/ c ? c. How far from Earth (as measured in the Earth frame) did you travel before turning around (give the answer in light years (ly ) in the Earth frame - hint the speed parameter tells you the speed in units of light years per year)?