Q1. A thermos contains 175 cm3 of coffee at 85° C. To cool the coffee, you drop two 13-g ice cubes into the thermos. The ice cubes are initially at 0° C and melt totally. What is the final temperature of the coffee?
Q2. A shopper in a supermarket pushes a loaded 36 kg cart with a horizontal force of 12 N.
The acceleration of gravity is 9.81 m/s2.
Disregarding friction, how far will the cart move in 3.5 s, starting from rest?
Give answer in units of m.
Q3. The K-shell ionization energy of copper is 8979 eV. The L-shell ionization energy is 951 eV. Determine the wavelength of the Kα emission line of copper. What should be the minimum voltage be on an x-ray tube with a copper target in order to see the Kα line? (Imagine that the copper atom is in ground state.)