Question

1. describe an example (with numerical values) where an object has an average velocity is zero but the average speed is 100 km/h

Explanation:

Average velocity is displacement over time ($v_{avg}=\frac{\Delta x}{\Delta t}$), and average speed is total distance over time ($s_{avg}=\frac{d}{\Delta t}$). If an object moves in a round - trip (e.g., from point A to point B and back to A), displacement ($\Delta x$) is zero (since the starting and ending positions are the same), but the distance ($d$) is non - zero.

Let's assume the distance from A to B is $d_1 = 100$ km. The total distance $d=2\times100$ km (going from A to B and then from B to A). Let the time taken for the whole trip be $t = 2$ h.

The average speed $s_{avg}=\frac{d}{t}=\frac{200\space km}{2\space h}=100$ km/h. The displacement $\Delta x=x_{final}-x_{initial}=0$ (if A is the initial and final position), so the average velocity $v_{avg}=\frac{\Delta x}{t}=\frac{0}{2\space h}=0$ km/h.

Answer:

An object travels from point A to point B (distance \(d_1 = 100\) km) and then back from point B to point A. The total distance \(d = 200\) km and the time taken \(t=2\) h. The average speed \(s_{avg}=\frac{200\space km}{2\space h}=100\) km/h, and the average velocity \(v_{avg}=\frac{0}{2\space h}=0\) km/h (since displacement \(\Delta x = 0\) as the object returns to the starting point).