Burst of Water Pipes - Essay Example

Thus, it would help to allow dripping of the faucet to dissolve the ice and prevent the growing volume of ice to bring about any further pressure against pipe walls. 

1. After a cold night, you will often find mist hovering over a lake. Explain why.

At night, the cooling of air happens at a speed greater than the cooling of water. Then from the surface of the lake, warm water vaporizes and blends with the colder air above it and due to the resulting temperature difference, warm water cools off becoming moisture in the form of droplets that suspend in the air. This suspension is actually the ‘steam fog’ which people often view as mist just on top of the lake’s surface.

2. A man who is 6 ft tall is standing in front of a plane mirror that is 2 ft in height. If the mirror is placed with its bottom edge 4 ft above the floor on a wall that is 5 ft away, how much of his image (i.e. what length of himself) can the man see? (Assume that his eyes are at the top of his head). If the man moves to a point 10 ft directly away from the wall, with the mirror staying in place, how much of himself can he now see? You must show all of your work, including sketches, to get full credit.

image

man

4 feet

2 feet

   |------------------- ---  5 feet   ------------------------|

Using the magnification formula:  

                                    M  =  |di / d0|  =  |I / O| 

Where I and O both refer to the heights of the image and the man, respectively, while ‘di’ and ‘d0’ are the distances of each from the mirror. Using a ruler to scale, the reflection is 2.4 feet away from the mirror, so

                        di  =  2.4 feet   ;   d0  =  5 feet   ;   I  =  ?   ;   O  =  6 feet

                                    (2.4 feet) / (5 feet)   =   I / (6 feet)

I  =  2.88 feet   à  which is about 48% of the man’s height

On the other hand, when the man is 10 feet away from the mirror, di =  5.25 feet, so that

                                    (5.25 feet) / (10 feet)  =  I / (6 feet)

                        I  =  3.15 feet  à  which is about 52.5% of the man’s height 

3. Light passes from a crown glass container into the water. Will the angle of refraction be
   (1) greater than,  (2) equal to, or  (3) less than the angle of incidence? Explain your answer.

In this scenario, the index of refraction of water is 1.33 @ room temperature whereas a typical crown grass has an index of refraction = 1.52, so when Snell’s law   n1*sinθ1  =  n2*sinθ2   is applied, the angle of refraction (θ2) would be greater than the angle of incidence (θ1).