Physics 609
Galileo and Einstein-- 3 Credits

Sample Question and Answer

This is a sample of a question from a homework assignment and the type of answer graders are looking for

1) Celestial Journal report. This question and problem is to get you started in creating your celestial journal. Describe how you are going about making the measurements of the angle of the sun, and give your results for at least one measurement. Describe how you measured the angle of the sun with the horizon near noon. Do not look at the sun to make this measurement. A simple method, as described in class, makes use of the shadow of objects. A vertical stick on level ground (fire hydrant, traffic sign) casts a shadow pointing north at noon. If you measure the height of the stick h, and the length of the shadow d, then the angular height of the sun is the angle whose tan equals h/d. Using a hand calculator evaluate tan-1(h/d) and that is the angle of the sun. You can also use a windowsill on the south-facing side of a building: the length of its shadow on the floor (toward north, not necessarily perpendicular to the wall) is d, and its height above the floor is h.

Key: 1) Find something that will be of constant height every day, such as a lamp post around your yard or school, your window sill if it faces south, etc…) 2) Measure its height. 3) Measure the length of its shadow. 4) The height of the sun is Q = tan-1(object height / object shadow). The angle is in radians. Convert it to degrees by multiplying it by 180/3.14.

• Question and Answer