Answer:
The contribution of the wavelets lying on the back of the wave front is zero because of something known as the Obliquity Factor. It is assumed that the amplitude of the secondary wavelets is not independent of the direction of propagation, Sources: byju's.com
Answer:
The ratio of the momentum imparted to gun #1 to that imparted to gun #2 is equal to 2 : 1
Explanation:
Detailed explanation and calculation is shown in the image below
Answer:

Explanation:
Hello.
In this case, since the force is defined in terms of the mass and acceleration by:

We can easily compute the mass by solving for it:

Whereas the force is 182 N (kg*m/s²) and the acceleration is 13 m/s², therefore, we obtain:

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Answer:
The unit of energy is joule which depends upon the fundamental unit kg, m and sec. So, the unit of energy is a derived unit.
Explanation:
Answer: 11 km/h at 339° compass
Explanation:
A sees B moving south at 0 km/h
A is moving north at 12cos30 = 10.392 km/h
Therefore B must be moving north at 10.392 k/h
A is moving east at 12sin30 = 6 km/h
B appears to be moving west at 10 km/h
Therefore B must be moving west at 10 - 6 = 4 km/h
B is moving v = √(4² + 10.392²) = 11.135... 11 km/h
θ = arctan( -4 / 10.392) = -21.05 = 339°