Question

The chart shows different speeds at which theoretical spacecraft are traveling horizontally. The speeds are represented as percentages of the speed of light the spacecrafts are traveling, where 0.20c = 6 × 107 m/s.

A 2 column table with 4 rows. The first column is labeled spacecraft with entries W, X, Y, Z. The second column is labeled Percentage of Speed of Light with entries 0.95 c, 0.40 c, 0.10 c, 0.69 c.
Which spacecraft appears the longest to an outside observer?

W
X
Y
Z

Answer 1

Y

Because moving objects are length-contracted by the factor sqrt(1 − v^2/c^2), the slower the craft the less contraction. 0.10c (Y) is the smallest speed, so it appears longest.