The position-time graph for a ball on a track is shown below.
(a) What is the ball's velocity at 4s?
(b) At what time(s) is the ball approximately travelling at -10m/s?
(c) From t = 3 to 7s, what is the sign of the acceleration?

FIGURE EX1.18 shows the motion diagram of a drag racer. The camera took one frame every 2 s. (b) Make a position-versus-time graph for the drag racer. Because you have data only at certain instants, your graph should consist of dots that are not connected together.

FIGURE EX2.4 is the position-versus-time graph of a bicycle. What is the bicycle's velocity at (a) t = 5s

FIGURE EX2.4 is the position-versus-time graph of a bicycle. What is the bicycle's velocity at (c) t = 30s

Which motion diagram best represents the following event: a skier skis down a slope with constant speed?

A cat walks in a straight line, which we shall call the x-axis, with the positive direction to the right. As an observant physicist, you make measurements of this cat's motion and construct a graph of the feline's velocity as a function of time (Fig. E2.30). (d) Assuming that the cat started at the origin, sketch clear graphs of the cat's acceleration and position as functions of time.

A cat walks in a straight line, which we shall call the x-axis, with the positive direction to the right. As an observant physicist, you make measurements of this cat's motion and construct a graph of the feline's velocity as a function of time (Fig. E2.30). (a) Find the cat's velocity at t = 4.0 s and at t = 7.0 s.

A physics professor leaves her house and walks along the sidewalk toward campus. After 5 min it starts to rain, and she returns home. Her distance from her house as a function of time is shown in Fig. E2.10. At which of the labeled points is her velocity (e) decreasing in magnitude?