Question

question 5 (1 point) saved
a polar bear starts at the north pole. it travels 1.0 km south, then 1.0 km east, then 1.0 km north, then 1.0 km west to return to its starting point. this trip takes 45 min.
what was the bears average velocity?
0 km/h
0.09 km/h
4.5 km/h
5.3 km/h
question 6 (1 point)
if you run a complete loop around an outdoor track (400 m), in 100 s, your average velocity is
0.25 m/s.
4.0 m/s.
40,000 m/s.
zero.
question 7 (1 point)
if the position versus time graph of an object is a vertical line, the object is
moving with constant non - zero speed.
moving with constant non - zero acceleration.
at rest.
moving with infinite speed.

Explanation:

Question 5

Step1: Recall velocity definition

Average velocity is displacement over time. Displacement is the straight - line distance from start to end.
The polar bear starts at the North Pole and returns to the starting point, so displacement \(d = 0\space km\).

Step2: Calculate average velocity

The formula for average velocity \(v=\frac{d}{t}\). The time \(t = 45\space min=\frac{45}{60}=0.75\space h\), and \(d = 0\space km\). So \(v=\frac{0}{0.75}=0\space km/h\).

Step1: Recall velocity definition

Average velocity is displacement divided by time. When you run a complete loop around a track, your starting and ending points are the same. So displacement \(d = 0\space m\).

Step2: Calculate average velocity

The formula for average velocity \(v=\frac{d}{t}\). The time \(t = 100\space s\), and \(d = 0\space m\). So \(v=\frac{0}{100}=0\space m/s\).

Step1: Analyze position - time graph

The slope of a position - time graph gives velocity. The formula for slope (velocity) is \(v=\frac{\Delta x}{\Delta t}\), where \(\Delta x\) is the change in position and \(\Delta t\) is the change in time.
For a vertical line, \(\Delta t = 0\) (since the time does not change while the position changes).

Step2: Calculate velocity

Using \(v=\frac{\Delta x}{\Delta t}\), if \(\Delta t = 0\), then \(v=\frac{\Delta x}{0}\), which means the velocity is infinite (because any non - zero \(\Delta x\) divided by zero is infinite).

Answer:

0 km/h

Question 6