# Homework Help: Waves and Sound

1. Jan 15, 2016

### Sace Ver

1. The problem statement, all variables and given/known data
The wavelength of a water wave is 4.4m and it's period is 1.5s.
(a) what is the speed of the wave.
(b) the time required for the wave to travel 100m.
(c) the distance travelled by the wave in 1min.

2. Relevant equations
v=λ/T

3. The attempt at a solution
(a) v=λ/T
v= 4.4m x 1.5s
v= 6.6m/s

Not sure how to complete questions (a) and (b).

2. Jan 15, 2016

### Staff: Mentor

The equation says to divide, but you multiplied.

Use the units to check your calculations. velocity is in m/s, wavelength is in m, and the period is in units of seconds. The units have to work out, or you have made a math error (like multiplying instead of dividing)...

3. Jan 15, 2016

### Sace Ver

Oops will fix right now.

4. Jan 15, 2016

### Sace Ver

Okay I got 2.93m/s. What I me
I meant to say not sure how to solve (b) and (c).

5. Jan 15, 2016

### Staff: Mentor

You just need the equation relating distance, speed and time. Use units to help you figure out the equation. What are the units of distance, speed and time? What equations can you write with those quantities so that the units are the same on both sides of the = sign?

6. Jan 15, 2016

### SteamKing

Staff Emeritus
If I'm walking down a road at 2 m/s, how long does it take me to walk 100 m? How far do I walk in 1 minute?

7. Jan 15, 2016

### Sace Ver

Not sure if I did this correctly.

(a) v=λ/T
v= 4.4/1.5
v= 2.93m/s

(b)t=d/v
t= 100m/2.93m/s
t= 34.13s

(c) d=vt
d= (2.93m/s)(60s)
d= 175.8m

Did I do it correctly?

8. Jan 15, 2016

### Staff: Mentor

Looks good to me. See how carrying units along in the equations helps to keep things straight?

9. Jan 15, 2016

### Sace Ver

Yess thanks for the help