Answer:
Your answer would be C, Radio waves.
Explanation:
Rolling friction .<span> the force that slows down the movement of a rolling object</span>
sliding friction.
Sliding friction : The opposing force that comes into play when
one body is actually sliding over the surface of the other body
is called sliding friction. e.g. A flat block is moving over a
horizontal table.
Kinetic or dynamic friction: If the applied force is increased further
and sets the body in motion, the friction opposing the motion is called
kinetic friction
Answer:
a) 



b) 
Explanation:
From the exercise we got the ball's equation of position:

a) To find the average velocity at the given time we need to use the following formula:

Being said that, we need to find the ball's position at t=2, t=2.5, t=2.1, t=2.01, t=2.001



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b) To find the instantaneous velocity we need to derivate the equation


Momentum is a product of mass and the velocity thus the momentum will be 5100*12 = 61200 kgm/s
Radio waves and visible light, as we perceive it, are both part of the EM spectrum. The only difference between them in terms of our perception is that we don't have receptors to 'see' radio waves. That's where radio receivers come into the picture*, to convert radio waves into sound impulses that we can hear.