cud u tell me about ref. frames in a very simple way?

Answer 1

A frame of reference is a way to see how vectors (like velocity and acceleration) can be measured.

It's hard to explain in words, so let me give you a simple example.

Suppose you are traveling in a car going 40 mph. A car next to you is traveling 45 mph. Since you are traveling 40 mph, your frame of reference shows that that car next to you is only traveling 5 mph (the difference of the two speeds). This makes sense because the car traveling next to you is only moving ahead of you at a slow rate.

Now let's change the frame of reference. Suppose you are a pedestrian at a crosswalk and you see these two cars passing
by. Since you are at a stationary position, the cars would be traveling at 40 and 45 mph respectively. Because you are stationary and at a different frame of reference, the speed changes relative to that frame.

Now's let's change the frame of reference one more time. Suppose you are in a car traveling 40 mph south. You pass by a car traveling 45 mph north. Because of your frame of reference, when you pass by the car, you see the car actually traveling (40-[-45]= 85) 85 mph! Because of your frame of reference, you actually see the car traveling faster than it really is.

Hope this explanation helps.

Answer 2

A reference frame is something against which position and velocity are measured. For example the reference frame for measuring the speed of your car is the road. If your speedometer reads 60 miles per hour it means that your car's location is changing one mile every minute as measured against the road. But another frame might be the car itself. A fly in the car is flying at 10 MPH inside the car, but it is going 70 MPH over the road as it flies from the back to the from of the car and only 50 MPH as it flies from the front to the back of the car.

An inertial frame is one that is not accelerating. The car is an inertial from if it drives at constant speed in a straight line. Objects in an inertial frame obey Newton's laws. The first law is that an object at rest tends to remain at rest in the same location unless acted on by a force. This property is called inertia, from which we get the term "inertial frame". In a car driving in a straight line at 60 MPH, you can set a cup of water on the floor and it stays there, unless you pick it up or bump it. But if the car turns a corner, or the driver hits the brake, then the car is no longer an inertial frame. The cup can fall over without being touched due to virtual forces imposed on it by the acceleration of the car. (slowing down and turning a corner are considered acceleration in physics.)

Answer 3

Maybe this http://www.physicsforums.com/showthread.php?t=133099 will help to explain.
I wouldn't know how to simplify it more....