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A car is 200 metres behind the bus, which is also at rest. Both start moving at the same time, but with different forward accelerations. The acceleration of the bus is 2\; m/s^{2}  and that of the car is 4\; m/s^{2}. The car will overtake  the bus after

Option: 1

120\; s


Option: 2

15\; s


Option: 3

10\sqrt{2\ }s


Option: 4

110\; s


Answers (1)

best_answer

Acceleration of car , a_c=4\ ms^{-2}

And, Acceleration of bus , a_b=2\ ms^{-2}

Now,

Initial gap between the bus and car is:

S_{cb}=200\ m

Acceleration of car with respect to bus is:

a_{cb}=\ a_c-a_b=\ 2\ ms^{-2}

Initial velocity:

u_{cb}=0\ and\ t=?

Thus, 

S_{cb}=u_{cb}\times t\ +\frac{1}{2}a_{cb}\ t^2

Or, 200=0\times t\ +\frac{1}{2}\times2\times t^2

Or, t^2=200

I.e. t=10\sqrt2\ s

 

Posted by

Suraj Bhandari

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