Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
Home  >>  JEEMAIN and AIPMT  >>  Physics  >>  Class11  >>  Motion in a Straight Line
0 votes

Straight from rest and moving with a constant acceleration , a body covers certains distance L in time t. What is the time taken by the body to cover the second half portion of this journey ?

$\begin{array}{1 1}(A)\;t \bigg(\frac{\sqrt 2 -1}{\sqrt 2}\bigg)\\(B)\;t^2 \bigg(\frac{\sqrt 2 -1}{\sqrt 2}\bigg) \\(C)\;t^3 \bigg(\frac{\sqrt 2 +1}{\sqrt 2}\bigg) \\(D)\;t \bigg(\frac{\sqrt 2 +1}{\sqrt 2}\bigg)\end{array} $

Can you answer this question?

1 Answer

0 votes
Let the time taken to cover the first half portion of the journey be $t_1$ and for the second half portion be $ t_2$ . Then
For the first half-journey, putting
$S= L/2,u=0$ etc. in $S= ut+ \large\frac{1}{2} $$at^2$, we get $\large\frac{L}{2} $$=0+\frac{1}{2} $$at_1^2$
$\large\frac{L}{2}$$=0+ \large\frac{1}{2}$$at_1^2$
As the time to complete the whole journey is t, therefore ,
$L= 0+ \frac{1}{2}$$at^2$
Dividing both equations :
$L= 0+ \large\frac{1}{2}$$=> t_1 =\large\frac{t}{\sqrt{2}}$
$t_2= (t-t_1)=t- \frac{t}{\sqrt 2}=t \bigg[\large\frac{\sqrt 2-1}{\sqrt 2}\bigg]$
Hence A is the correct answer.
answered Jul 18, 2014 by meena.p

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, NEET Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App