When the gas in a balloon is heated, the balloon expands. what are the correct signs of heat and work for this change?
a. +q, -w
b. -q, +w
c. +q, +w
d. -q, -w

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?