Question #ceaab

Feb 28, 2017

Average velocity for trip: $\approx 71 \text{km/hr}$

Explanation:

A car moves due east at 93 km/hr for 64 minutes and then turns around and moves west at 72 km/hr for 10 minutes, what is the average velocity for the entire trip?

• Distance travelled in E direction:

$93 \cdot \frac{64}{60}$km

• Distance travelled back in W direction:

$72 \cdot \frac{10}{60}$km

Net travel ( ie displacement ) in E direction is:

$93 \cdot \frac{64}{60} - 72 \cdot \frac{10}{60}$km

$= \frac{436}{5}$km $= 87.2$km

Time for entire trip: $64 + 10 = 74 \min = \frac{74}{60} h r$

Average velocity for trip $= \text{displacement"/"time}$

$= \frac{87.2}{\frac{74}{60}} \approx 70.702 \text{km/hr}$