# Homework Help: Help pleeeese (validity of f=ma, mass of diff.temp objects)

1. Mar 15, 2005

### kiwikiwi79

help pleeeese~~ (validity of f=ma, mass of diff.temp objects)

1. is f=ma valid in all situations? explain your reasons~
2. is the mass of a hot frying pan different from a cold frying pan? why?

thank you~~~

2. Mar 15, 2005

### thomate1

Newtons laws are obeyed only in inertial frames.In an accelarated frame they are not obeyed.
For simplicity consider u are travelling in a trian with an accelaratin a. If u look a tree outside u will find that tree is also accelarating wrt u. But no force is acting on the tree. So F = ma is not valid.

3. Mar 15, 2005

### thomate1

Consider the second question,

When we saz E= mc2 we mean that mass and energy are two diff forms of same thing. U can say that frying pan has more energy or more mass than ordinary one.

4. Mar 16, 2005

### krab

kiwikiwi: I see you've asked a number of questions, all of which look like verbatim from a text book. Please read the sticky at the top of this homework forum.