lost with this question

[tolga]

A student at the Australian institute of Sport was able to establish that during flight, a 2.0kg shot experienced a force due to air resistance that was proportional to the square of its speed. The formula Fa=3.78times10^-5v^2 was dtermined, where Fa is the force due to air resistance and v is the instantaneous speed of the shot. The shot-put in one particular toss was launched at 7.5m/s at an angle of 36degrees to the horizontal.
a)calculate the maximum force due to air resistance that the shot experiences during its flight.
b)Calculate the value of the ratio of the forces acting on the shot as it is tossed: Fg/Fa(max) What does your answer tell you about these forces
can somebody tell me what this question is saying because i don't know what Fa anf Fg is and can't solve the problem

[/0]

I think is the force due to gravity and is the maximum force due to air resistance.


a) The maximum speed is at the start of the flight, since it is decelerating during its ascent and its maximum speed while falling will be lower due to air resistance. So the max force will be for the initial speed.

[tolga]

i keep getting 1.3times 10^-3 when ido that but the answer says 2.1times10^-3 and is Fa also known as drag force and Fg known as weight

[/0]

is Fa also known as drag force and Fg known as weight

Yes, those are also common names for them

For part a) what speed did you use?
I used v = 7.5m/s and got .

[tolga]

why did you use the resultant vector force not the vertical componet for speed?

[/0]

Air resistance opposes the 'resultant' motion of the particle.  Whichever direction the particle moves in, air resistance will act in the opposite direction. This is the same for friction in 2D.