(hrwc10p29) An early method of measuring the speed of light makes use of a rotat
ID: 1347201 • Letter: #
Question
(hrwc10p29) An early method of measuring the speed of light makes use of a rotating slotted wheel. A beam of light passes through a slot at the outside edge of the wheel, as in the figure, travels to a distant mirror, and returns to the wheel just in time to pass through the next slot in the wheel. One such slotted wheel has a radius of 5.0 cm and 600 slots at its edge. Measurements taken when the mirror was L = 450 m from the wheel indicated a speed of light of 3.00×108 m/s. What was the (constant) angular speed of the wheel?
What was the linear speed of a point on the edge of the wheel?
Explanation / Answer
time taken by the light between the wheel to mirror is t = 2L/c
t = 2* 450/3e8
t = 3 us
Distance D between the slots = 2piR/N
d = 2 *3.14 * 0.05/600
d = 0.523 mm
angular displacement theta = W t
so W = 2pi/Nt
W = 2*3.14 /(600 * 3e -6)
W = 3488.88 rad/s
----------------
as V = r W
linear spedd V = 0.05 * 3488.88
V = 174.44 m/s
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.