Two cars start from the same spot and travel along perpendicular roads. One travels at 30 km/h and the other at 40 km/h. Find the distance between them after 1 hour. MCQ with Answer and Explanation
Two cars start from the same spot and travel along perpendicular roads. One travels at 30 km/h and the other at 40 km/h. Find the distance between them after 1 hour.
A. 45 km
B. 60 km
C. 55 km
D. 50 km
Answer: Option D
Solution (By JKSSB Mock Tests)
In 1 hour, the first car travels 30 km and the second car travels 40 km. Direct distance = sqrt(30^2 + 40^2) = sqrt(900 + 1600) = sqrt(2500) = 50 km.
Explanation:
Relative speed = 100 / 6 = 50/3 m/s = (50/3) * (18/5) = 60 km/h. Since the train passes him from behind (same direction), Relative Speed = Speed of train - Speed of man => 60 = Speed of train - 5 => Speed of train = 65 km/h.
A person walks from his house to his office at a speed of 4 km/h and reaches 10 minutes late. If he walks at 5 km/h, he reaches 5 minutes early. Find the distance between his house and office.
Explanation:
Let original speed be s. 360 / (s - 10) - 360 / s = 2 => 180 / (s - 10) - 180 / s = 1 => 180(10) = s(s - 10) => 1800 = s(s - 10). Solving s^2 - 10s - 1800 = 0 gives (s - 45)(s + 40) = 0. Since speed is positive, s = 45 km/h.
No comments yet. Be the first to start the discussion!