A403.0-kg copper bar is melted in a smelter. the initial temperature of the copper is 320.0 k. how much heat must the smelter produce to completely melt the copper bar? for solid copper, the specific heat is 386 j/kg • k, the heat of fusion is 205 kj/kg, and the melting point is 1357 k.

Boxing gloves are padded to lessen the force of a blow. (a) calculate the force exerted by a boxing glove on an opponent’s face, if the glove and face compress 7.50 cm during a blow in which the 7.00-kg arm and glove are brought to rest from an initial speed of 10.0 m/s. (b) calculate the force exerted by an identical blow in the gory old days when no gloves were used and the knuckles and face would compress only 2.00 cm. (c) discuss the magnitude of the force with glove on. does it seem high enough to cause damage even though it is lower than the force with no glove?

Explain why electric current cannot exist if a current doesn't have a voltage source.

Panel bc in fig. p2.76 is semi-circular, with the 3 meter radius and horizontal straight edge through point b. compute (a) the hydrostatic force of the water on the panel, (b) its center of pressure, and (c) the moment of this force about point b. assume atmospheric pressure on the dry side of the panel