SHM, Waves, Thermo, E&M Practice Problem Workbook

4.50 m
MECHANICS PRACTICE PROBLEM SETS 24
11. A person measures the width of a swimming pool to be 4.50 meters. This same
person notices that the bottom edge of the pool is just visible at an angle of 12.0°
above the horizontal. Knowing that the n water = 1.33 and n air = 1.33, calculate the depth
of the pool.
Answer: depth = 4.15 m
12. The critical angle of a certain piece of plastic in air is 30°. What is the critical angle if
the plastic is immersed in water Answer: θ 2 = 42°
13. In the Fall 2006, the Sky Mirror sculpture was opened in Rockefeller Center in New
York City. Standing three stories tall and weighing 23 tons, its convergent side faced
the Rockefeller Center and its divergent side faced Fifth Avenue.
a. A taxi on Fifth Avenue is located 38 m from the divergent side of the
sculpture and its image is one-fifth the size of the taxi. Determine the focal
length of the mirror.
Answer: f = -9.5 m
b. What is the image size and image distance of the 260-m tall Rockefeller
Center if it is located an estimated distance of 95 meters from the convergent
mirror surface. Assume the focal length of the two sides have the same
magnitude.
Answer: d i = 11 m; h i = -29 m
14. The widest cinema screen in the world was reportedly constructed in New Zealand in
2007. The screen is 30.6 meters (100 feet) wide. Images from a 35-mm wide film are
projected onto this screen. Suppose that the screen in the theater is located a distance
of 46 m from the projector. Determine the magnification of the image and the focal
length of the lens system.
Answer: M = -870; f = 53 mm
15. The divergent lens has a focal point that is located 17.8 cm from the lens. A virtual
image is produced on the same side of the lens as the object at a distance of 7.23 cm
from the lens. Determine the object distance. Answer: d o = 12.2 cm
Gamzon & Gregorian-Michaelsen 6/13/12