Question

What is the average speed and average velocity at t = 30s respectively?

• A. 1 m/s, - 0.33 m/s
• B. 1m/s, -1m/s
• C. 2m/s, -0.25 m/s
• D. 2 m/s, 0

Answer 1

The correct option is A

1 m/s, - 0.33 m/s

For speed

Average speed = $\frac{totaldistance}{totaltime}$

Particle travels 10 m from 0 to $t_B$ then stays at rest from $t_B$ to $t_C$, then another 10 m from $t_C$ to t = 20s.

Then another 10 m in the opposite direction from t = 20s to 30s.

$\therefore Averagespeed=\frac{10+0+10+10}{30}=\frac{30}{20}$

= 1 m/s

For average velocity,

Total average velocity,

Total displacement at t = 30, = -10m

Average speed = $\frac{totaldistance}{totaltime}$

= $\frac{-10}{30}=\frac{-1}{3}=-0.33m/s$.