# Physics

posted by .

There is a 1.2 m distance between a crest and an adjacent trough in a series of waves on the surface of a lake. In 30s, 35 crests pass a buoy anchored in the lake. What is the speed of these waves?

• Physics -

The wavelength is the crest-to-crest distance, which would be 2.4 m.

Multiply that by frequency to get the wave speed.

The frequency is 35/30 = 1.17 Hz

• Physics -

1.2x2x34/30

Distance between two crest points is 1.2x2
Distance between 35 crest points is 1.2x2x34.
Note a crest is a point. One may not measure the time duration of a crest point.

I've just noted that waves and crests are both used in such problems. The total distance is commonly given by multiplying the number, or 35 in this case. To me, this is really confusing!

## Similar Questions

1. ### Physics

There is a 1.2 m distance between a crest and an adjacent trough in a series of waves on the surface of a lake. In 30s, 35 crests pass a buoy anchored in the lake. What is the speed of these waves?
2. ### physics

A group of swimmers is resting in the sun on an off shore raft. They estimate that 1.1m separates a trough and an adjacent crest of surface waves on the lake. In addition, they count 23 crests that pass by the raft in 15.7seconds. …
3. ### Physics

A student reading his physics book on a lake dock notices that the distance between two incoming wave crests is about 0.65 m, and he then measures the time of arrival between the crests to be 1.8 s. What is the approximate speed of …
4. ### Physical Science

waves moving on a lake have a speed of 2.0 m/s and a distant of 1.5m between adjacent crest. what is the frequency of the waves?
5. ### physics

A group of swimmers is resting in the sun on an oﬀ-shore raft. They estimate that 2.85 m separate a trough and an adjacent crest of surface waves on the lake. They count 13 crests that pass by the raft in 20 s. How fast are …
6. ### Physics!! HELP

A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves …
7. ### PHYSICS! I CAN NOT GET

A group of swimmers is resting in the sun on an off-shore raft. They estimate that 2.5 m separates a trough and an adjacent crest of surface waves on the lake. They count 15 crests that pass by the raft in 15 s. How fast are the waves …
8. ### Physics

A group of swimmers is resting in the sun on an off shore raft. They estimate that 2.9 meters separates a trough and an adjacent crest of surface waves on the lake. In addition, they count 12 crests that pass by the raft in 16 seconds. …
9. ### Science

You are sitting in a rowboat on a lake, watching waves created by a passing motorboat. If you count 4 crest pass every second, and the crests are 5 feet apart, what is the speed of the water waves?
10. ### Physics

Pepe and Alfredo are resting on an offshore raft after a swim. They estimate that 3m separates a trough and an adjacent crest of surface waves on the lake. They count 14 crests that pass by the raft in 20 seconds. Calculate how fast …

More Similar Questions