Here's what you need to know about waves:
Wavelength = (speed) / (frequency)
Now ... The question gives you the speed and the frequency,
but they're stated in unusual ways, with complicated numbers.
Frequency: How many each second ?
The thing that's making the waves is vibrating 47 times in 26.9 seconds.
Frequency = (47) / (46.9 s) = 1.747... per second. (1.747... Hz)
Speed: How far a point on a wave travels in 1 second.
The crest of one wave travels 4.16 meters in 13.7 seconds.
Speed = (4.16 m / 13.7 sec) = 0.304... m/s
Wavelength = (speed) / (frequency)
Wavelength = (0.304 m/s) / (1.747 Hz) = 0.174 meter per second
Explanation:
If you cannot visualize it, just assume that the distance from station A to B is 420km. Each half is 210km.
When the car travels from A to B, it takes 420/30 = 14 hours.
When the car travels from B to the halfway point, it takes 210/30 = 7 hours.
When the car travels from the halfway point to A, it takes 210/70 = 3 hours.
Total time taken = 14 + 7 + 3 = 24 hours.
Total distance = 420km * 2 = 840km.
Hence, the average speed of the car is 840/24 = 35km/h.
Well, the acceleration is the difference of speeds divided by the time period.
.
One rev/s is
, so our final result is
.
