1) In a racetrack, cars are expected to be moving with a speed
of approximately 120m/s. If the turns in the track are quarter
circles with radius 150m, at what angle should the tracks be banked
so that the cars can make the turn without using friction? 2) A 1000kg train engine is pulling a 5000kg boxcar. In this
boxcar is a 100kg crate of apples. The train is accelerating at
2m/s². Draw a complete freebody diagram of each object (the engine,
the car, and the crate). The friction between the boxcar and the
tracks is negligible, but other frictions are not. Find the values
of each force, and indicate which pairs of force are
action/reaction pairs. 3) A box is sitting on the side of a hill that makes an angle
20° with the horizontal. There is a horizontal wind blowing the box
up the hill. If the box has a mass of 30kg, and the coefficient of
kinetic friction between the box and the mountain is 0.1, how
strong is the force from the wind?