Alexis was interested in the way mirrors reflect. the living room of alexis' house had one big window in the front, and a very large mirror on the back wall. alexis hypothesized that the room would heat up faster in the morning with the mirror on the wall than it would if the mirror were covered with a sheet that was the same color as the walls.
what will make alexis' hypothesis valuable?
a it cannot be valuable because the investigation is in her house and not in the science lab.
b any testable hypothesis is valuable.
c it will be valuable only if it is proved incorrect.
d it will be valuable only if it is proved correct.

weight of any object is given by

w = m*g

where m is mass of the object and g is the acceleration due to gravity.

for earth the value of g is 9.8 m/s^2 so

w=117.6 n m=12 g=?

117.6=12g => g=9.8 m/s^2

which is the force of gravity on earth.

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.