An object that absorbs all radiation falling on it, at all wavelengths, is called a black body. When a black body is at a uniform temperature, its emission has a characteristic frequency distribution that depends on the temperature. Its emission is called black-body radiation
hope it helps
The speed of an object at rest is 0 m/s. We can use logic to figure this out. Hope this helps!
Explanation:
a) Balloon is being thrown down and is speeding up;
mg > 
b) Balloon is in the air on its way down and moving with constant speed.
=mg
c) The Balloon is on the ground and rest instantaneously
mg = Normal
d) Balloon is moving slowly downward;
e) Because, at the peak of trajectory drag force is 0.
Drag force = 0
I actually believe for the first question, it would be complete destructive interference as the amplitude and the approximate wavelength for each are the same and will completely or entirely cancel out, rather than simply decreasing or lowering the amplitude as in the bottom question.
The amplitude for the first will be 0, as the 2 waves will cancel each other out. The amplitude of the second, will be 3x, I believe, assuming the amplitude of the first is 2x and the second is 1x, in a constructive interference, I believe the amplitudes would add up.
Likewise for the bottom, I believe you would be subtracting the supposed amplitude of the first which is 2x from 1x which would be 1x.
