Awindow has a glass surface of 2907 cm2 and a thickness of 5.6 mm. find the rate of energy transfer by conduction through this pane when the temperature of the inside surface of the glass is 71◦f and the outside temperature is 81 ◦f. assume the thermal conductivity of window glass is 0.8 j/s · m · ◦ c . answer in units of kw

part bfind the rate of energy transfer for the same inside temperature and an outside temperature of 0◦f.

2.30714 W

-16.38071 W

Explanation:

k = Heat conduction coefficient = 0.8 W/(m·°C)

A = Area = 2907 cm²

l = Thickness = 5.6 mm

= Outside temperature

= Inside temperature

Rate of heat transfer is given by

The rate of energy transfer is 2.30714 W

The rate of energy transfer is -16.38071 W

given data:

determine the horse power (h.p) = ?

force applied to move the box(f) = 10 pounds,

box lifted from a distance         (d) = 3 feet

time taken to lift                         (t) = 10 sec,

the horse power is defined as amount of work required to move a load. the horse power is equal to 550 foot-pound per second

                  1 h.p   = 550 foot-pound/second

it can also be defined as the the load that need to be move a body for certain distance in a certain amount of time.

mathematically,

                      h.p = (force × distance)/ time

                            = (10 × 3)/ 10

                            = 30/10

                            = 3 foot -pound/sec

hence, the horse power is needed to move the box is 3 foot-pound/second

important note: 1 h.p = 550 foot-pound/second = 746 watts