Inside a calorimeter is 100 g of water at 39.8 ºC. A 10 g object at 50 ºC is placed inside of a calorimeter. When equilibrium has been reached the new temperature of the water and metal object is 40 ºC. What type of metal is the object made from?

An alpha particle with kinetic energy 12.5 mev makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude l = p0 b, where p0 is the magnitude of the initial momentum of the alpha particle and b=1.40×10−12 m. (assume that the lead nucleus remains stationary and that it may be treated as a point charge. the atomic number of lead is 82. the alpha particle is a helium nucleus, with atomic number 2.) what is the distance of closest approach?