Answer:
32.5 m/s
Explanation:
Velocity of a wave = frequency * wavelength
Velocity = 65 /s * 0.5 m
Velocity = 32.5 m/s
Answer:
636.619772368 A
Explanation:
= Torque = 
B = Magnetic field of Earth = 
A = Area
d = Diameter = 20 cm
Current is given by

The current is 636.619772368 A
Answer:

Explanation:
First of all, let's convert from nanometres to metres, keeping in mind that

So we have:

Now we can convert from metres to centimetres, keeping in mind that

So, we find:

Machines are never 100% efficient because they are made by humans and we make errors and nothing we make is perfect, that's why the machines we build are not 100% accurate or efficient.