Suppose it takes 4 erg of work to stretch a spring 10 cm beyond its natural length. How much more work is needed to stretch it 4 cm further?

How would a small bar magnet be oriented when placed at position x?

A47.2 g block of copper whose temperature is 480 k is placed in an insulating box with a 91.8 g block of lead whose temperature is 200 k. (a) what is the equilibrium temperature of the two-block system? (b) what is the change in the internal energy of the two-block system between the initial state and the equilibrium state? (c) what is the change in the entropy of the two-block system? the heat capacities of copper and lead are 386 j/kg·k and 128 j/kg·k, respectively.

Which is the most accurate name for the covalent compound p2o3?