Question

You have already traveled east in your car 100km in 1hr and then south 100km in 2hrs. To get back home, you then drive west 100km for 3 hours and then go north 100km in 4hrs. You would say your average velocity for the total trip was....

A. 20km/hr
B. 40km/hr
C. 60km/hr
D. 100km/hr
E. None of the above

Answer 1

You first travel 100km in 1 hour which makes your velocity 100km/h (100/1=100)
You then travel 100km in 2 hours which makes your velocity 50km/h (100/2=50)
You then travel 100km in 3 hours which makes your velocity 33.3km/h (100/3=33.3)
Finally, you travel 100km in 4 hours which makes your velocity 25 km/h (100/4=25)

Add up all your velocities (100+50+33.3+25) which makes 208.3
You then divide it by 4 since you have 4 travels.
208.3 / 4 = 52,075

So I would say the answer is E in this case since none of the answers is close to 52km/hr

Answer 2

Since your start and end points for the try are the same point, your displacement for the trip is zero. Since the magnitude of velocity is (displacement) divided by (time), the average velocity is also zero. The correct choice is (E).