Recent content by craigman

If the block were in contact with the ground and not the wall, the friction force would be calculated by 9.81*0.5*u=friction force. In this case gravity does not actually push the block into the wall and the force of m*g is acting perpandicular to the wall, which means only the horizontal force...

does anyone know this stuff?

Hey check this: http://img47.imageshack.us/img47/7376/mirrorgs9.jpg ok so you focal distance is going to be 160cm because we can say that the 180=3x and the ratio between the sizes of the two objects is 2:1

I can't get the correct answer i just don't know why

More Calcs http://img204.imageshack.us/img204/8186/calcsud2.jpg

~~Just guessing~~ Fish-not sure wood iron- the amount of air being displaced by the wood means it has more buoyancy. So there must be slightly more wood than iron. pennies- the electrons are temporarly taken from the penny. work- it must be loosing more heat energy to it's surroundings than what...

I think the friction is related only to the 12N and not to the mg component. So the reaction force at the wall is equal to 12N. 12*us=7.2N (b) and we can disprove (d) and (e) by stating 0.5*9.81=4.9N The mass of the block is not great enough to overcome friction. Short answer: (b)

Homework Statement http://img136.imageshack.us/img136/7465/problemchapter5150152gh1.jpg http://img515.imageshack.us/img515/5239/knownxd2.jpg Homework Equations aA=aB+aA/B aA=aAN+aAT aN=\omega 2r aT=\alpha r The Attempt at a Solution...