Question

Car moving on a highway at 50 km/hr sees a truck in front of it carrying a plane mirror at its back, moving in the same direction. If the driver of the car sees the reflection of car coming towards him at 50 km/hr, what is the speed of the truck?​

Answer 1

Answer:

The speed of the truck is 100 km/hr.

Given:

Car moving on a highway at 50 km/hr sees a truck in front of it carrying a plane mirror at its back, moving in the same direction.  

To find:

If the driver of the car sees the reflection of car coming towards him at 50 km/hr, what is the speed of the truck

Solution:

Let x is the distance between the car and mirror.

Then 2x is the distance between car and its image, because for a plane mirror, object distance is equal to image distance.

So the speed of the truck =  2$\times$ speed of the car  

                                          = 2 $\times$ 50

                                          = 100 km/hr.