A van is traveling on a road at a speed of 55 km/h. A girl sitting near the driver of the van throws a paper airplane to a boy a
2 answers:
Answer:
53 km/h
Explanation:
Let's take as positive direction the direction in which the van is moving. In this case, we can write as follows:
- Velocity of the van relative to the road:
- Velocity of the paper airplane relative to the van: (with a negative sign since it is moving into opposite direction)
Therefore, the velocity of the paper airplane relative to the road (stationary observer) will be
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Answer:
d= 1.56 m
Explanation:
In order to have a constructive interference, the path difference between the sources of the sound, must be equal to an even multiple of the semi-wavelength, as follows:
⇒ d = d₂ - d₁ = 2n*(λ/2)
The minimum possible value for this distance, is when n=1, as it can be seen here:
dmin = λ
In any wave, there exists a fixed relationship between the wave speed, the frequency and the wavelength:
v = λ*f
If v = vsound = 343 m/s, and f = 220 1/s, we can solve for λ:
λ =
⇒ dmin =λ = 1.56 m