13. A bullet moving with velocity 235m/s strikes a ballistic pendulum of mass 1.2 kg and becomes embedded. The pendulum rises to a height of 23cm from its original position.
a) What was the velocity of the pendulum bullet system after the collision?
b) Calculate the mass of the bullet.
Show all work please!

Work = force × a. work b. energy c. distance d. momentum

Hydrogen and helium are both members of?

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.