A space probe is 15.6 m in length when measured at rest.What length does an observer at rest measure when the probe is going by at a speed of 0.740c?
A)23.2 m
B)10.5 m
C)8.0 m
D)11.5 m
E)21.1 m

Question

A space probe is 15.6 m in length when measured at rest.What length does an observer at rest measure when the probe is going by at a speed of 0.740c?
A)23.2 m
B)10.5 m
C)8.0 m
D)11.5 m
E)​21.1 m

Quizplus · Accepted Answer

We can use the formula for length contraction:

L' = L√(1-v^2/c^2)

where L is the rest length (15.6 m), v is the velocity (0.740 c), c is the speed of light, and L' is the length measured by the observer.

Plugging in the values:

L' = 15.6 √(1-(0.740)^2/(1)^2) = 10.5 m

Therefore, the observer at rest would measure the length of the space probe as 10.5 m. The correct choice is B.

A Space Probe Is 15