Motion in a Straight Line - Result Question 20

20. A particle moves in a straight line with a constant acceleration. It changes its velocity from 10ms1 to 20ms1 while passing through a distance 135m in t second. The value of t is:

[2008]

(a) 10

(b) 1.8

(c) 12

(d) 9

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Answer:

Correct Answer: 20. (d)

Solution:

  1. (d) Initial velocity, u=10ms1

Final velocity, v=20ms1

Distance, s=135m

Let, acceleration =a

Using the formula, v2=u2+2as

a=v2u22s

=(20)2(10)22×135=4001002×135

or, a=3002×135=150135=109ms2

Now, using the relation, v=u+at

t=vua=201010/9=1010×9sec=9sec.



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