If you are walking at constant velocity of 5 km/h and a car passed you by at the speed of 20 km/h from behind, what is the car's velocity from your viewpoint? i also want 2 know why?
2007-05-12 03:45:05 · 5 answers · asked by Varun N 1 in Science & Mathematics ➔ Physics
It is all about relative speed. If you are standing still then the car passes you at 20 mph. If you are running at 5 mph, then it is 20 mph - 5 mph = relative speed 15 mph. That is relative to you. On the other hand, if the car is approaching your position, and you are standing still he is still coming at 20 mph. If you are running, then he is coming at 25 mph.
2007-05-12 04:02:03 · answer #1 · answered by tashiasdad 2 · 0⤊ 0⤋
The relative velocity (whose numerical value is the speed) will be 15 km/h since the car is travelling in the same direction as you. If the car approached you from the opposite direction, the relative velocity would be 20 + 5 = 25 km/h.
2007-05-12 11:22:28 · answer #2 · answered by Swamy 7 · 0⤊ 0⤋
The cars velocity is actually 25 kph but since you are treveling at 5 kph it would seem to be going 20 kph. Add your peed to the cars speed and you get 25.
2007-05-12 10:55:11 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The car's speed from your view point is (20-5)km/h i.e. 15km/h .This is due to relativity.According to relativity the position of an object is never absolute. It is only relative to a reference point.In your case you are the reference point and the speed of the vehicle becomes 15km/h.
2007-05-12 11:12:01 · answer #4 · answered by Happy 3 · 0⤊ 0⤋
The cars velocity from your viewpoint is 20km/hr, because you have set yours at 5km/hr relative to the ground.
Relativity - relative to what? If you say you are moving 5, it is moving 20. If you say you are standing still, it is at 15.
2007-05-12 10:51:53 · answer #5 · answered by John Q Harris 3 · 0⤊ 0⤋