Question

5.2.1 study: describing motion
you walk 800 m
south in 10
minutes.
velocity = 80 m/min
south
you run 10 m
east and then 10
m west in 30
seconds.
velocity = 0 m/s
you run 10 km
north and then 5
km south in 1
hour.
velocity = 5 km/h north
hint

Explanation:

Step1: Calculate velocity for the first case

Velocity formula: \(v=\frac{\Delta x}{\Delta t}\). Here, \(\Delta x = 800m\) (south), \(\Delta t=10min\).
\(v=\frac{800m}{10min}=80m/min\) (south)

Step2: Analyze displacement for the second case

Run \(10m\) east then \(10m\) west. Net displacement \(\Delta x=10m - 10m=0m\). Using \(v = \frac{\Delta x}{\Delta t}\), with \(\Delta t = 30s\), \(v=\frac{0m}{30s}=0m/s\)

Step3: Calculate displacement and velocity for the third case

Displacement \(\Delta x=10km-5km = 5km\) (north). Time \(\Delta t = 1h\). Using \(v=\frac{\Delta x}{\Delta t}\), \(v=\frac{5km}{1h}=5km/h\) (north)

Answer:

The first case uses the formula \(v=\frac{\Delta x}{\Delta t}\) to get \(80m/min\) south. The second case has net displacement \(0\) leading to \(0m/s\). The third case calculates displacement as \(5km\) north and velocity as \(5km/h\) north using \(v=\frac{\Delta x}{\Delta t}\)