Question

Fig. 6.38 shows the graph of the x-coordinate of a particle going along the x-axis as a function of time. Find (a) the average velocity during 0 to 10 s, (b) instantaneous velocity at 2, 5, 8 and 12 s.

Answer 1

(a) Average velocity $=\frac{Totaldisplacement}{Totaltime}=\frac{100}{10}=10$ m/s

(b) Instantaneous velocity is given by the slope of the x vs t graph at that point instantaneous velocity at $2$ sec $=\frac{50}{2.5}=20$m/s

Instantaneous velocity at $5$ sec $=\frac{0}{5}=0$ m/s

Instantaneous velocity at $8$ sec $=\frac{100-50}{10-7.5}=\frac{50}{2.5}=20$ m/s

Instantaneous velocity at $12$ sec $=\frac{0-100}{15-10}=\frac{-100}{5}=(-20$ m/s$)$.