Answer to Question #203964 in Physics for Rethabile

Question

24. While observing the obelisk in Saint Peter’s Square in Vatican City, you stand at the edge of the shadow it is casting across the ground, which is about 120 m long. While kneeling, you estimate your line of sight with the top of the obelisk to be about 12o above the horizontal. Approximately how tall is the obelisk? (3)

A) 9.6 m C) 23.1 m E) 26 m 

B) 120 m D) 190 m 

25. A partly full paint can has 2.75 liters of paint left in it. What is volume of the paint in cubic centimeters? (3)

A) 2.75 x 10-3 cm3 C) 275 x 10-3 cm3 E) 27.5 x 103 cm3

B) 2.75 cm3 D) 2.75 x 103

Answer 1

24) We can find the height of the obelisk from the geometry:

$$tan\theta=\dfrac{h}{L},$$ $$h=Ltan\theta=120\ m\cdot tan12^{\circ}=26\ m.$$

Therefore, the correct answer is (E) 26 m.

25)

$$2.75\ L\cdot\dfrac{0.001\ m^3}{1\ L}\cdot\dfrac{10^6\ cm^3}{1\ m^3}=2750\ cm^3=2.75\cdot10^3\ cm^3.$$

Therefore, the correct answer is (D) 2.75 x 10³ cm³.