Worksheets9 Relativistic time and length
Total questions: 8
Worksheet time: 4mins
On the spaceship travelling at 0.8c, what is the distance Betty measures to star A (6 ly away in Earth's reference frame), and much time passes for her to reach the star system?
The distance is 3.6 lightyears, so it takes her 4.5 years.
The distance is 6 lightyears which takes her 4.5 years.
The distance is 5 lightyears, so it takes her 6.25 years.
The distance is 6 light years which takes her 7.5 years
What is the resolution to the paradox, that Jo (on Earth) should age more than Betty (moving away at 0.8c in the rocket) in Jo's reference frame and Betty should age more than Jo in Betty's reference frame (in which Earth is moving away from her at 0.8c)?
Jo ages more when Betty is travelling away from Earth and Betty ages more on the return trip
Special relativity only applies to inertial (non-accelerating) reference frames and the rocket accelerates at the beginning and end of its journey.
Earth cannot move at 0.8c therefore only Jo ages
Jo's Newtonian momentum is zero so her relativistic momentum is also zero
Muons created by cosmic radiation 10 km above the surface of the Earth travelling at 0.98c have a half-life of 1.56 x 10-6 s (in the muon's inertial frame). Approximately how many half lives would it take for a muon to travel 10km in Newtonian travel?
22
10
3
4.5
If Penny, carrying a 40 m pole, is running at 0.87c can observer Bill standing at the center of a 20m barn simultaneously close both the doors with the pole inside as Penny runs through?
No, because in Bill's reference frame the barn is 9.9 m and the pole is 40 m
No, because in Bills's reference frame the barn is 20 m and the pole is 40 m
Yes, because in Bill's reference frame the pole is 19.7 m and the barn is 20 m
Yes, because in Bill's reference frame the barn is 40.6 m and the pole is 40 m
A spaceship, moving away from the Earth at a speed of 0.9c, fires a light beam backward. An observer on Earth would see the light arriving at a speed of
1.9c
0.1 c
c
more than 0.1c but less than c
A train has a rest length of 100 m. Traveling at a very high velocity, it goes through a tunnel of length 80 m. Observers located at both ends of the tunnel note that at one instant the train appears to exactly fit within the tunnel.
What is the velocity of the train expressed in units of c?
0.333 c
0.50 c
0.60 c
0.80 c
0.866c
Muons created by cosmic radiation 10 km above the surface of the Earth travelling at 0.98c have a half-life of 1.56 x 10-6 s (in the muon's inertial frame).
In the muons' frame of reference, how far above the surface are they created?
1.99 km
50 km
10 km
4.5 km
