A train 100 m long crosses a pole in 5 seconds. Its speed in km/h is MCQ with Answer and Explanation

Explanation:
Endoscope uses optical fibres for internal examination.

Explanation:
In uniform circular motion, speed is constant but velocity direction changes continuously, producing centripetal acceleration. Magnitude a = v²/r, direction always towards the center of the circle. This acceleration changes velocity direction without altering speed. Tangential acceleration would change speed, but here speed is constant. Formula derivation: From vector analysis of velocity change over small time interval. Exam tip: Remember 'centripetal' means 'center-seeking'; this concept is fundamental for rotational dynamics questions in competitive exams.

Explanation:
η = 1 - T₂/T₁ = 1 - (300/400) = 1 - 0.75 = 0.25 = 25%. Wait, T₁ high temp 400 K, T₂ low 300 K, so η = 1 - 300/400 = 0.25 = 25%. Option A is 25%. Let's correct answer A. I'll set option A: 25%.