Share
Explore BrainMass

Spacing of Rails/Removal of Heat

1. Segments of 12mt long steel rails are laid end to end when the temperature is -12 degree C. A space is left between rail segments to allow for thermal expansion.

a. If they are to just touch when the temp is 33degree C, the spacing is ---------

2. A freezer has a coefficient of performance of 2.40 and can convert 1.80 kg of water at 25 degree C to ice at -5 degree c in 1 hr.

a. The heat removed per hour is ------------ and

b. The electrical energy consumed per hour is---------

3. Divers are sealed in deep-dive research vessel on the deck of the mother ship and lowered to a depth of 4000 mt into the ocean. The density of sea water = 1.03 * 10^3 kg/mt^3

a. the force of the water on a 30.5 cm diameter port window is ------------N or --------atm

Solution Preview

1. a. Given,

Length of rail, L = 12mt

Initial temperature, T1 = -12 degree C
Final Temperature, T2 = 33 dgree C

Change in temp, dT = 33 - (-12) = 45 degree C

The change in length of the steel road is given by,
dL = alpha * L * dT

where alpha is the coefficient of linear expansion of steel.

dL = alpha * 12 * 45
dL = alpha * 540

Let alpha for steel = 11* 10^-6 /degree C

Therefore, dL = 11*10^-6 * 540

==> dL = 5.940 * 10^-3 m
==> dL = 5.9 mm

Therefore, space to be left ...

Solution Summary

343 words answer 3 questions on thermal expansion, coefficient of performance and the force of water on a submerged window.

$2.19