The speed of a wave can be calculated using the formula:
\[ \text{Speed} = \text{Frequency} \times \text{Wavelength} \]
Let's calculate the speed for each wave:
-
Wave 1:
- Frequency = 120 Hz
- Wavelength = 5 m
- Speed = 120 Hz × 5 m = 600 m/s
-
Wave 2:
- Frequency = 90 Hz
- Wavelength = 7 m
- Speed = 90 Hz × 7 m = 630 m/s
-
Wave 3:
- Frequency = 140 Hz
- Wavelength = 2 m
- Speed = 140 Hz × 2 m = 280 m/s
-
Wave 4:
- Frequency = 70 Hz
- Wavelength = 8 m
- Speed = 70 Hz × 8 m = 560 m/s
Now, we compare the speeds:
- Wave 1: 600 m/s
- Wave 2: 630 m/s
- Wave 3: 280 m/s
- Wave 4: 560 m/s
The wave with the fastest speed is Wave 2, which has a speed of 630 m/s.
So, the correct response is: wave 2