David Sang and Darrell Hamilton Solutions for Chapter: Describing Motion, Exercise 3: Exercise 2.2

The table shows the time taken for each of three cars to travel $100 \mathrm{m}$. Write the name of the fastest car. Complete the table by calculating the speed of each car. Give your answers in $\mathrm{m}/\mathrm{s}$ and to one decimal place.

A stone falls $20 \mathrm{m}$ in $2.0 \mathrm{s}$. Calculate its average speed as it falls.

If a stone covers $25 \mathrm{m}$ in $1.0 \mathrm{s}$ of its fall uniformly, calculate the stone's average speed during the $3 \mathrm{s}$ of its fall.

 Explain why we can only calculate a stone's average speed during its fall.

State a stone's average velocity during the free fall. Explain why you have stated it the way you have.

The microwaves used in police speed detection devices travel at $300000 \mathrm{km}/\mathrm{s}$. Calculate how long it takes for the pulse of microwaves from the device to return to the device after it has been emitted and reflected from an object $200 \mathrm{m}$ away.