Question

Two cars A and B are approaching each other
head-on with speeds 20 m/s and 10 m/s
respectively. When their separation is x then A and
B start braking at 4 m/s2 and 2m/s respectively,
Minimum value of X to avoid collision is
(1) 60 m
(2) 75 m
(3) 80 m
(4) 90 m​

Answer 1

Dear Students,

● Answer -

(2) X = 75 m

◆ Explanation -

Let s1 & s2 be stopping distances for car A & car B respectively.

Applying Newton's 3rd law of kinematics to car A,

v1² = u1² + 2as

0 = 20² + 2×(-4) × s

s1 = 400 / 8

s1 = 50 m

Applying Newton's 3rd law of kinematics to car B,

v2² = u2² + 2as

0 = 10² + 2×(-2) × s

s2 = 100 / 4

s2 = 25 m

Therefore, minimum separation between cars at the time of breaking is -

X = s1 + s2

X = 50 + 25

X = 75 m

Hope I was useful.

Answer 2

Answer:

_____________X = 75 m ____________