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 1.611 443 948 872 75 ± 4 milliseconds, where the trailing ± 4 indicates the uncertainty in the last decimal place (it does not mean ± 4 ms). **PLEASE WRITE STEPS CLEARLY**

(a) How many rotation does the pulsar make in 21.0 days?

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

(c) What is the associated uncertainty?

Explanation / Answer

a)

The number of rotations in 21 days N is given by

N = (21 days) / (time per rotation).

I will convert to seconds: 21 days = (21 days) x 86400 s / days = 1814400 s

N = (1.8144 x 10^6) / (1.61144 x 10^-3 s/rev)

N = 1.123 x 10^9 rev

b)

Time for 10^6 rotations = (10^6 )(1.61144394887275 x 10^-3) = 1611.44394887275 s

c)

The uncertainty is 4 in the last digit or ± 4 x 10^-14 s

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

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