To move a refrigerator of mass 150 kg into a house, a mover puts it on a dolly and covers the steps leading into the house with a wooden plank acting as a ramp. The plank is 7.8 m long and rises 3.3 m. The mover pulls the dolly with constant velocity and with a steady force 1500 N up the ramp. a)How much work does he perform? The acceleration of gravity is 9.8 m/s. Answer in units of J.
b)What is the minimal work required to lift the refrigerator into the house? Answer in units of J.

While strolling downtown on a saturday afternoon, you stumble across an old car show. as you are walking along an alley toward a main street, you glimpse a particularly stylish alpha romeo pass by. tall buildings on either side of the alley obscure your view, so you see the car only as it passes between the buildings. thinking back to your physics class, you realize that you can calculate the car's acceleration. you estimate the width of the alleyway between the two buildings to be 6 m. the car was in view for 0.6 s. you also heard the engine rev when the car started from a red light, so you know the alpha romeo started from rest 4 s before you first saw it. find the magnitude of its acceleration.