You are walking towards teh back of the bus that is movind forward with a constant velocity. descriube your motion relative to the bus and relative to a oint on the groun.

When walking towards the back of a bus while it moves forward its apparent velocity seems slower than it actually is with respect to the ground.

Explanation:

When a someone follows a moving bus from behind by walking then the apparent speed of the bus is slightly slower by the same magnitude as the speed of walking because both are moving in the same direction.This is the concept of relative velocity when the apparent velocity of the same object appears different to different viewers at the same time being on different frame of motion.When the same bus is observed from a point on the road the speed of the bus will appear greater than the former case discussed above because the bus here is moving with respect to a stationary observer.