Time standards are now based on atomic clocks. A promising second standard is ba

Question

Time standards are now based on atomic clocks. A promising second standard is based on pulsars, which are rotating neutron stars (highly compact stars consisting only of neutrons). Some rotate at a rate that is highly stable, sending out a radio beacon that sweeps briefly across Earth once with each rotation, like a lighthouse beacon. Suppose a pulsar rotates once every 1.587 343 948 872 75 ± 4 ms, where the trailing ± 4 indicates the uncertainty in the last decimal place (it does not mean ± 4 ms).

(a) How many times does the pulsar rotate in 7.00 days?

(b) How much time does the pulsar take to rotate exactly one million times? (Give your answer to at least 4 decimal places.) s

(c) What is the associated uncertainty of this time? ± s

Missed and confused on B and C

Explanation / Answer

(a.) Find out how many ms are in one day:
(24hr/1 day) x (60min/1hr) x (60s/1min) x (1000ms/1s)
= 86,400,000 ms/day
Divide that number by 1.587 343 948 872 75... to get the number of rotations in one day. It equals about 54430547.37 Multiply this by 7 to get the number of rotations in 7 days which is eqal to 381013831.6 ms = 381013.8316 s

(b.) I'll go with 1.0 x 10^6. Anyway...
Multiply 1.587 343 948 872 75 ... by 10^6. You get about 1.587 343 948 872 75 x 10^6. This is how many milliseconds it takes to rotate 10^6 times. Convert this number into seconds to get the final answer.

answer = 1.587 343 948 872 75 x 10^3 s

(c.) Uncertainty of one rotation: 3 x 10^-14 ms
Multiply (1.0 x 10^6) by (3 x 10^-14 ms).= 3 x 10^-8 ms = 3 x 10^-11 s

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.