Motion in a Straight Line - Result Question 8

8. A car covers the first half of the distance between two places at 40km/h and other half at 60km/h. The average speed of the car is

(a) 40km/h

(b) 48km/h

(c) 50km/h

(d) 60km/h

[1990]

Topic 2: Non-uniform motion

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Answer:

Correct Answer: 8. (b)

Solution:

  1. (b) Total distance =s;

Total time taken

=s/240+s/260=5s240=s48

Average speed = total distance  total time 

=ss/48=48km/h

vav=2v1v2v1+v2=2×40×6040+60=48km/h



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