Define power in a single sentence.
A cyclist moves along a horizontal road. Fig. 3.1 shows how the speed $v$ changes with time $t$. The cyclist keeps the power constant and, after some time, reaches a steady speed of $12\,\text{m s}^{-1}$. Describe and explain the cyclist’s motion.
A cyclist moves along a horizontal road. Fig. 3.1 shows how the speed $v$ changes with time $t$. The cyclist keeps the power constant and, after some time, reaches a steady speed of $12\,\text{m s}^{-1}$.
At the steady speed of $12\,\text{m s}^{-1}$ the resistive force is $48\,\text{N}$. Show that the cyclist’s power is about $600\,\text{W}$. Explain your working.
Use Fig. 3.1 to show that the cyclist’s acceleration when his speed is $8.0\,\text{m s}^{-1}$ is about $0.5\,\text{m s}^{-2}$.
The cyclist and bicycle together have mass $80\,\text{kg}$. Calculate the resistive force $R$ acting on the cyclist when his speed is $8.0\,\text{m s}^{-1}$. Use the acceleration value from (iii).
Use the information in (ii) and your answer to (iv) to show that, in this situation, the resistive force $R$ is proportional to the cyclist’s speed $v$.