Question

Two cars A and B are moving in same direction
with velocities 30 m/s and 20 m/s. When car A
is at a distance d behind the car B, the driver of
the car A applies brakes producing uniform
retardation of 2 m/s2. There will be no collision
when :-
(1) d < 2.5 m
(2) d > 125 m
(3) d > 25 m
(4) d < 125 m​

Answer 1

Explanation:

Distance required to catch the speed of car B with given retardation can be found using

v^2=u^2+2as

20^2=30^2+2(-2)s

4s=30^2-20^2

$$\Rightarrow s= 125m $$

So the distance sholud be greater than 125 m

⇒d>125m

Therefore, A is correct option

Answer B

Answer 2

Answer:

Distance required to catch the speed of car B with given retardation can be found using

v

2

=u

2

+2as

⇒20

2

=30

2

+2(−2)s

⇒4s=30

2

−20

2

$$\Rightarrow s= 125m $$

So the distance sholud be greater than 125 m

⇒d>125m