Let us discuss Physics questions

In this thread, let us discuss some interesting questions related to Physics. One person will post a question, others will answer and thus that question and its answers will be discussed. Once, the discussion on any question is over, then another question will be posted (by me or anybody who wishes).
Let me post the first question.
You are travelling in a bus. You are facing the direction in which the bus is moving. There is a video camera inside the bus. The camera is tied very tightly to a wall on the bus. It is so tightly tied that there is no relative movement between the camera and the bus. The camera is focussed on you. Initially the bus is stationary. You are sitting quietly and the camera is recording you. Suddenly the driver starts the bus. The camera continues to record you. Once you reach your destination, then you check the recording of the camera. You find that when the driver started the bus, then the camera recorded you falling back.
Why did camera make such a recording?
This question is related to Newton's laws.

Originally posted by: amail1601

Next question:

When a person diets, is their goal to lose mass or to lose weight? Explain.

The camera was tied to the bus so it moved with the bus. On the other hand the person was at rest but the bus(and the camera) moved. [/quote]
Let me put it another way. In Physics, there is nothing called absolute motion. Movement is always relative. For example, I am sitting in my chair. I am at rest in Earth's frame of reference but moving in Sun's frame of reference. So, frame of reference is important. When we are talking about camera's recordings, then we have to see from camera's frame of reference.

You are saying that camera moved with the bus. Moved in which frame of reference? In camera's frame it did not move at all. Then, in which frame did it move? Please let me know where you have fixed the frame of reference.

[quote]I told you...last time I read abt this was in class 9th...3 years ago 😆 I should be given some marks for attempting 😉 [/quote]

Yes, you are right. 😊 Thanks for attempting. But the discussion on this question is still not over.😉

Originally posted by: lrllover

uff kya baat hai yaha par physics classes bhi start ho gayi cool 👏 [/quote]

Interesting hai na?😊

[quote]well inertia and relative motion are the reasons for this observation

when the bus starts to move the lower part of the body which is in contact with the floor moves along with the bus hence there is no relative motion between the camera and the lower part of the body but the upper part of the body tends to remain at rest due to Inertia of rest......as a result of which the person appears to fall backwards w.r.t. the camera's frame of reference

You are saying that bus starts to move. In which frame of reference does it move? Is it camera's frame?