A trolley has a mass of 20 kg. The static coefficient of friction between the trolley and the ground is 0.6. The dynamic (kinetic) coefficient of friction between the trolley and the ground is 0.5 (g = -9.8m/s2) a. How much pushing force must be applied to the trolley to initiate movement in the horizontal direction on level ground? 3 points b. After the movement is initiated, how much pushing force must be applied to the trolley to result in an acceleration of 2 m/s2 in the horizontal direction on level ground? 3 points c. How much pushing force must be applied to the trolley to result in acceleration of 1 m/s2 up a ramp of 30 degrees. 4 points d. How much pushing force must be applied to the trolley to result in acceleration of 1 m/s2 down a ramp of 30 degrees. 4 points