a 5.0 kg toy car can move along an x axis; fig. 9-50 gives fx of the force acting on the car, which begins at rest at time t 0. the scale on the fx axis is set by in unit-vector notation, what is at (a) t 4.0 s and (b) t 7.0 s, and (c) what is at t 9.0 s?
