During the falling down, two forces are present: gravitational force and air resistance.
So, the net force = mg - f = 12*9.8 - 27 = 90.6 N, the positive sign indicates the direction is pointing towards the center of the earth, which is the same as gravitational force
I think the corect answer would be C. When a police officer receives information that you are speeding in your vehicle, she is using the frequency of the wave to measure the Doppler Effect. As the speed of a vehicle increases, the greater the change of the frequency of the waves would be transmitted to the radar guns which is being used by the police officer. Doppler effect is an effect that is observed in sound and light waves as these waves move away or to the direction of the observer. This is being used in many applications like in astronomy, weather balloons, the radar guns,and for underwater researches.
The answer to your question is B- They both described the inner part otherwise known as the inner core.
The inner core is hotter than the surface of the sun. The inner core is made out of iron and nickel. The inner core is extremely hot and is the last layer. It is a solid because of all the pressure from the other layers putting there weight onto this layer.
