Question

A car is moving on a straight line at a speed of 50 km/h and a truck is ahead of a car and having the large plane mirror fixed vertically on the back of truck. Truck is running at a speed of 70 km/h. For a stationary observer s†an ding between car and truck. What is the speed of image of car in the mirror? (1) 40 km/h (2) 70 km/h (3) 20 km/h (4) 90 km/h

Answer 1