The work done to pull the sled up to the hill is given by

where
F is the intensity of the force
d is the distance where the force is applied.
In our problem, the work done is

and the distance through which the force is applied is

, so we can calculate the average force by re-arranging the previous equation and by using these data:
Answer:
The minimun height is 242 [m]
Explanation:
We can solve this problem by using the principle of energy conservation, where potential energy becomes kinetic energy. We will take the point where the Falcon reaches the speed of 69 (m/s), as the point where the potential energy is zero, i.e. it will be the reference point.
At the reference point all potential energy has been transformed into kinetic energy, therefore the kinetic energy can be calculated.
![E_{k}=0.5*m*v^{2} \\ where:\\v = velocity = 69 [m/s]\\m = mass = 480[g] = 0.480[kg]\\E_{k} = kinetic energy [J]\\E_{k} =0.5*0.48*(69)^{2} \\E_{k} =1142.64[J]](https://tex.z-dn.net/?f=E_%7Bk%7D%3D0.5%2Am%2Av%5E%7B2%7D%20%5C%5C%20where%3A%5C%5Cv%20%3D%20velocity%20%3D%2069%20%5Bm%2Fs%5D%5C%5Cm%20%3D%20mass%20%3D%20480%5Bg%5D%20%3D%200.480%5Bkg%5D%5C%5CE_%7Bk%7D%20%3D%20kinetic%20energy%20%5BJ%5D%5C%5CE_%7Bk%7D%20%3D0.5%2A0.48%2A%2869%29%5E%7B2%7D%20%5C%5CE_%7Bk%7D%20%3D1142.64%5BJ%5D)
Now we can calculate the elevation with respect to the reference point using the definition of the potential energy.
![E_{p}=m*g*h\\ E_{p}=E_{k} \\therefore\\h= E_{p}/(m*g)\\h= 1142.64/(.48*9.81)\\h=242[m]](https://tex.z-dn.net/?f=E_%7Bp%7D%3Dm%2Ag%2Ah%5C%5C%20E_%7Bp%7D%3DE_%7Bk%7D%20%5C%5Ctherefore%5C%5Ch%3D%20E_%7Bp%7D%2F%28m%2Ag%29%5C%5Ch%3D%201142.64%2F%28.48%2A9.81%29%5C%5Ch%3D242%5Bm%5D)
Answer:
Atmospheric Refraction is the bending of light rays when they pass through the layers of earths atmosphere
Explanation:
Hope this helps
W = mg, because you have the weight of the piano and if you just divide it by g that will give you the mass you need. The piano isn't accelerating right now in a way that you'd need to use F = ma.