Physics 103 : Discussion 2 6. The position versus time for a certain particle moving along the x axis is shown in Figure P2.6. Find the average velocity in the time intervals (a) 0 to 2.00 s, (b) 0 to 4.00 s, (c) 2.00 s to 4.00 s, (d) 4.00 s to 7.00 s, (e) 0 to 8.00 s. FIGURE P2.6 7. A tennis player moves in a straight-line path as shown in Figure P2.7. Find her average velocities in the time intervals (a) 0 to 1.0 s, (b) 0 to 4.0 s, (c) 1.0 s to 5.0 s, and (d) 0 to 5.0 s. FIGURE P2.7 9. Figure P2.9 shows a position-time graph for several trains traveling along a straight track. Identify the graphs that correspond to (a) forward motion only, (b) backward motion only, (c) constant velocity, (d) greatest constant velocity, (e) no movement. FIGURE P2.9 22. The velocity-time graph for an object moving along a straight path is shown in Figure P2.22. (a) Find the aver-age accelerations of this object during the time intervals 0 to 5.0 s, 5.0 s to 15 s, and 0 to 20 s. (b) Find the instantaneous accelerations at 2.0 s, 10 s, and 18 s. FIGURE P2.22 23. The engine of a model rocket accelerates the rocket vertically upward for 2.0 s as follows: At t = 0, its speed is zero; at t = 1.0 s, its speed is 5.0 m/s; at t = 2.0 s, its speed is 16 m/s. Plot a velocity-time graph for this motion, and from it determine (a) the average acceleration during the 2.0-s interval and (b) the instantaneous acceleration at t = 1.5 s.