1. If a 250 kg rock is sitting on the ledge of a cliff 295 meters high, then what is the potential energy of the rock?
2. A 275 kg rock is rolling faster and faster down the side of a mountain. At the bottom
of the mountain the rock has an instantaneous velocity of 3 m/s, at this moment what is
the kinetic energy of the rock?
3. A race car with a mass of 500 kg on a bridge 45 m above a river, what is the
potential energy of the car?
4. A race car with a mass of 500 kg is driving with an instantaneous velocity of 2.8 m/s,
what is the kinetic energy of the car?
5. Two blocks of wood with a mass of 0.02 kg are hanging 0.9 m above the floor, what
is the potential energy of the blocks of wood?
Mi

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.