HPS 0410 Einstein for Everyone

What Happens at High Speeds

According to special relativity, rods and clocks are affected by their motion. If a yardstick is moved rapidly along the direction of its motion, it contracts. If a clocks ticks once per second when it is at rest, it will tick more slowly when it is moving.

Moving rods and clocks

Velocity Fraction of Lightspeed β factor
(see below).		 Contracted length of yardstick
= β yards		 Time between ticks of clock
= 1/β seconds
100 mph .000000149 .99999999999998885 .99999999999998885yd
(Earth's diameter 7,926 miles loses 5.6 millionth inch)		 1.00000000000001115 sec
(One year loses 0.35 microseconds)
10,000 mi/sec



26,200 mi/sec .141 .99 .99 yd 1.01 sec
93,000 mi/sec




.866 .5 .5 yd 2 sec

.99 .141 .141 yd 7.1 sec

.995 .10 .10 yd 10.0 sec

.9999 .014 .014 yd 70.7 sec

1.0 (impossible) 0 0 yd infinity sec


Calculate β factor =√(1-(fraction of lightspeed2)).
i.e. Square root of (1 - square of fraction of lightspeed)
The speed of light is 186,000 miles per second.