A common example of radiation would have to be sunlight
So there are different ways this could be solved. I'll do try to explain it the way I was taught...
Simon is riding his bike at 12 km/hr relative to the sidewalk, away from where Keesha is.
Simon throws the ball at Keesha, at 5 km/hr.
Keesha sees the ball approaching her at (12-5) = 7 km/hr relative to the ground to her.
Therefore the answer is: 7 km/hr
I think A is the correct answer because its high is more higher compared to the others, and the mass really does not matter, to know the gravitational potential energy, we need to know how high the object is located because gravity does not show any favor to an object that has more mass or an object that doesnt
Where the displacement is a maximum the pressure is a minimum.
Where the displacement is zero, the pressure is a maximum.
