Question

2.9 A ball moves in a straight line (the r-axis). The Figure E2.9 graph in Fig. E2.9 shows this v, (m/s) ball's velocity as a function of time. (a) What are the ball's 3.0 average speed and average velocity during the first 3.0 s? (b) Suppose that the ball moved 1.0 in such a way that the graph seg- ment after 2.0 s was-3.0 m/s ol 1.0 instead of +3.0 m/s. Find the 2.0 t(s) 2.0 3.0 i ball's average speed and average velocity in this case.

Answer 1

Average speed and velocity from speed vs time graph

Distance covered in 3s d_0 - 2 = 2 times 2 = 4 m d_2 - 3 = 3 times 1 = 3 m so d = 4 + 3 = 7 m Hence average speed - V_avg = d/t = 7/3 V_avg = 2.333 m/s and average velocity V^vector_avg = d^vector/t = 7/3 i^^ V^vector_avg = 2.333 i^^m/s \r\n V_avg = 7/3 V_avg = 2.333 m/s and V^vector_avg = d^vector/t because d^vector_0 - 2 = 4 m d^vector_2 - 3 = -3 times 1 = -3 m so d^vector_0 - 3 = 4 - 3 = 1 m V^vector_avg = 1/3 = 0.333 m/s V^vector_avg = 0.333 i^^m/s