Physics 12 Activity
Why Don’t We Notice Time Dilation
Physicist: ________
1. Complete the chart below. Rewrite the first five speeds in terms of c. Calculate  for each speed. Sketch
a graph of  vs v (in terms of c).
Speed
Speed (in terms of c)
Fast Runners, 10 m/s
Fast Cars, 40 m/s
Fast Jets, 600 m/s
The Space Shuttle, 7860 m/s
Voyager Space Probe, 17000 m/s
TV screen electrons
X-Ray Machine Electrons
LHC protons
0.1 c
0.3 c
0.5 c
0.7 c
0.9 c
0.99 c
0.999 c
0.999 999 999 95 c
=
2. Should the first five  values you calculate be the same? Explain.
3. Offer a simple explanation for why relativistic effects are not noticed in daily life.
4. What happens to the size of  as v approaches the value c?
5. What does this tell us about the flow of time for a highly relativistic object (speeds close to c)?
6. Relativistic effects are important for GPS satellites which orbit at a similar speed to the space shuttle
relative to the ground. Precision timing is absolutely essential for determining an object’s location on
the earth. For a GPS satellite observed from the earth,  = 1.000 000 000 3.
a) Over the course of one day, how much time in seconds does the GPS clock gain or lose compared to
a ground clock? (Hint: you can’t plug that value of  into your calculator.)
b) How far does light travel during that time discrepancy? How would this affect GPS?