92q04.html

Physics Review Question

Unit: Mechanics
Year: 1992 Question#: 4
Question: A group of bike riders took a 4.0-hour trip. During the first 3.0 hours, they traveled a total of 50 kilometers, but during the last hour they traveled only 10 kilometers. What was the group's average speed for the entire trip?

(1 ) 15km/hr
(2 ) 30km/hr
(3 ) 40km/hr
(4 ) 60km/hr

What is this question really asking?

Explanation by: Michelle H

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Answer 1
15km/hr

CORRECT

This answer is correct because speed is calculated by dividing the total time that the trip took into the total distance of the trip. Speed=distance/time. Their average speed was calculated to be 15km/hr. return to top

Answer 2
30km/hr

INCORRECT

Looks like you just added the two distances and divided by two. THis would have worked if they had only been traveling 2 hours but they had been traveling four hours.
This answer is incorrect because average speed is calculated by dividing the total time that the trip took into the total distance of the trip. Speed=distance/time. return to top

Answer 3
40km/hr

INCORRECT

This answer is incorrect because speed is calculated by dividing the total time that the trip took into the total distance of the trip. Speed=distance/time. return to top

Answer 4
60km/hr

INCORRECT

This answer is incorrect because speed is calculated by dividing the total time that the trip took into the total distance of the trip. Speed=distance/time. return to top

What's this question really asking?

This question is asking the group's average speed for the entire trip. The question breaks their entire trip into two sections, make sure that you calculate the speed for the entire length of the trip, not just one part of it. return to top

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