Answer:
12.5
Step-by-step explanation:
Let individual time taken by Anthony, Brian and Chris = t1 , t2 , t3 respectively
So, total time taken by A & B = 1 / t1 + 1 / t2 , lets suppose = 10 {i}
Total time taken by A & C = 1 / t1 + 1 / t3 , lets suppose = 15 {ii}
Total time taken by B & C = 1 / t2 + 1 / t3 , lets suppose = 20 {iii}
From {i} , 1 / t2 = 10 - 1 / t1
From {ii} 1 / t1 = 15 - 1 / t3
By above two eqtns , 1 / t2 = 10 - (15 - 1 / t3)
1 / t2 = 1 / t3 - 5
Putting in {iii} , 1 / t3 - 5 + 1 / t3 = 20
2 / t3 = 25
t3 = 12.5
Answer: 54.88 mph
Step-by-step explanation: the Doppler effect formulae is given below as
f' = (v + vo) /(v - vs) × f
Where f' = observed frequency = 236 Hz,
f = frequency of sound source (stationary frequency) = 253 Hz.
v = speed of sound in air = 761 mph
Since the car (source) is moving away relative to the observer, vs will have a negative value (-vs)
vo = 0 mph ( since the observer is not moving)
By substituting the parameters, we have that
236 = (761+0)/(761 - (-vs)) × 253
236 = (761/ 761 +vs) × 253
By cross multiplication, we have that
236 × (761 +vs) = 761 ×253
761 + vs = 761 ×253/ 236
761 + vs = 192533/ 236
761 + vs = 815.88
vs = 815.88 - 761
vs = 54.88 mph
Answer:
radius= 5.1 cm
diameter=10.2cm
Step-by-step explanation:
