Question

(7) to keep an eye on all of her students during a test the physics teacher walks around the classroom as shown in the diagram below. if it takes the teacher 3.5 minutes to walk once around the classroom, what is the teachers average speed and velocity?

Explanation:

Step1: Calculate the distance

The teacher walks around a rectangle. The perimeter $d$ of the rectangle is calculated by $d = 2\times(10.5 + 8.0)$. So $d=2\times18.5=37\text{ m}$.

Step2: Convert time to seconds

The time $t = 3.5$ minutes. Since $1$ minute $= 60$ seconds, $t=3.5\times60 = 210\text{ s}$.

Step3: Calculate average speed

The formula for average speed $v_{s}$ is $v_{s}=\frac{d}{t}$. Substituting the values of $d = 37\text{ m}$ and $t = 210\text{ s}$, we get $v_{s}=\frac{37}{210}\approx0.088\text{ m/s}$.

Step4: Calculate average velocity

The teacher starts and ends at the same point. Displacement $\Delta x=0$. The formula for average velocity $v_{v}=\frac{\Delta x}{t}$. Since $\Delta x = 0$, $v_{v}=0\text{ m/s}$.

Answer:

Average speed: $0.088 \text{ m/s}$, Average velocity: $0 \text{ m/s}$