toasters

[eeyore]

what are the push or pull forces and friction in a toaster

[dinsdale]

Well, when you press the handle on the side down, you are pressing down a cage that is spring mounted on the base. this locks into position by a timer controlled lock. so you are the first push force pushing down, the resistance you feel is the push force of the springs pushing back up, so you need to apply more downward force than the upward force of the spring in order to insert the bread. once the timer lock releases the kinetic energy stored in the springs at the bottom of the cage (the extra enery you used in pushing the bread down there) is released and the springs push the cage back up. the cage then hits the top of its runner and locks again exerting a push upwards on the runner end, the runner end maching this force pushes downwards and the cage is then stationary, or held in equilibrium between the force needed to energise the springs and the constant down pulling of gravity. the toast carries on with its momentum, from the push force of the spring as there has been no downwards force applied to it by the runner stops so will jump, untill the force of gravity outweighs the energy provided by the springs of the toaster, causing the toast to either drop back into the cage or onto the worktop. of course as the cage is running on runners there will always be losses caused by friction, the runners sliding against each other change some of the engery used by the push pull motions of the toaster operation into heat, this energy is then wasted. another wastful aspect of this motion is the energy that is converted to sound, creating the noise of the toast popping up, so the energy you put into pushing the toast down is not returned in the upwards motion of the cage. as energy can never be created or destroyed, only changed to different types of energy, some of which we cant control, perpetual motion is impossible. hope this helps