Question 80: Motion in 1D

Question

A car is standing 200 m behind a bus, which is also at rest. The two start moving at the same instant but with different forward accelerations. The bus has acceleration 2 m/s2  and the car has acceleration 4 m/s2 . The car will catch up with the bus after a time of :

Accepted Answer

Acceleration of Car,  a
C
= 4 m/s
2
Acceleration of bus, a
B
= 2 m/s
2
Initial distance between them, S = 200 m
Acceleration of Car with respect to bus,
a
CB
= a
C
$$-$$ a
B
= 4 $$-$$ 2 = 2 m/s
2
As initially both  are at rest so, u
CB
= 0
$$	herefore\,\,\,$$ S = U
CB
$$ 	imes $$ t + $${1 \over 2}$$ a
CB
$$ 	imes $$ t
2
$$ \Rightarrow $$$$\,\,\,$$ 200 = 0 + $${1 \over 2}$$ $$ 	imes $$ 2 $$ 	imes $$ t
2
$$ \Rightarrow $$$$\,\,\,$$ t
2
= 200
$$ \Rightarrow $$$$\,\,\,$$ t = 10$$\sqrt 2 $$ sec.

Answer

$$\sqrt {110} \,s$$

Answer

$$\sqrt {120} \,s$$

Answer

$$10\,\,\sqrt 2 \,s$$

Answer

15 s

Motion in 1D

A car is standing 200 m behind a bus, which is also at rest. The two start moving at the same instant but with different forward accelerations. The bus has acceleration 2 m/s2 and the car has acceleration 4 m/s2 . The car will catch up with the bus after a time of :

Choose the correct answer: