A model toy car moves round a circular track with a steady speed of $0.50\,\text{m s}^{-1}$. It crosses a marked point on the track at time $t = 0$ and needs $40\,\text{s}$ to complete one full lap. The size of the average velocity of the car from $t = 0$ to $t = 20\,\text{s}$ is $v_{20}$. The size of the average velocity of the car from $t = 0$ to $t = 40\,\text{s}$ is $v_{40}$. What are $v_{20}$ and $v_{40}$?
- A$v_{20} = 0.32\,\text{m s}^{-1},\; v_{40} = 0$
- B$v_{20} = 0.32\,\text{m s}^{-1},\; v_{40} = 0.32\,\text{m s}^{-1}$
- C$v_{20} = 0.50\,\text{m s}^{-1},\; v_{40} = 0$
- D$v_{20} = 0.50\,\text{m s}^{-1},\; v_{40} = 0.50\,\text{m s}^{-1}$