When the Moon is on the horizon, it appears larger than when it is high in the sky. Why?
A. Its angular size is larger on the horizon.
B. This is an optical illusion.
C. When it is on the horizon, it is closer to us.
D. The brightness of the Moon makes it seem larger.
E. Earth's atmosphere acts like a lens, magnifying it.
Answer: B
You might also like to view...
The 500-m-long spaceship Springbrake is at rest on the planet Hitest for refueling. Another spaceship, Summerbrake, passes parallel to Springbrake at 0.600c. The crew on Springbrake measure the length of Summerbrake as it passes and find that the length they measure is exactly the same as the known 500-m rest length of Springbrake. If Summerbrake were at rest next to Springbrake, its length would then be measured to be
A. 180 m. B. 320 m. C. 500 m. D. 625 m. E. 781 m.
Series/Parallel Circuits: A 4.0-? resistor is connected with a 12-? resistor and this combination is connected across an ideal dc power supply with V = 6.0 V, as shown in the figure. When a total current I flows from the power supply, what is the current through the 12-? resistor?
A. 1.5 A B. 2.0 A C. 2.5 A D. 3.0 A E. 0.50 A
A spring-driven dart gun propels a 10. g dart. It is cocked by exerting a force of 20. N over a distance of 5.0 cm. With what speed will the dart leave the gun, assuming the spring has negligible mass?
What will be an ideal response?
Compared with the efficiency of a typical steam-electric generating plant, the efficiency of a typical hydro-electric generating plant is
A) smaller because a steam-electric converts thermal energy into non-thermal forms and the second law of thermodynamics implies that this is a highly efficient process. B) smaller, because only a small amount of the energy in the water behind a dam can be converted into electricity. C) greater because a hydro-electric plant uses the sun as its source of energy, rather than hard-to-obtain fossil fuels. D) about the same, because both are heat engines and so both have the large inefficiency implied by the second law of thermodynamics. E) greater because a hydro-electric plant is not a heat engine and so it does not have the large inefficiency implied by the second law of thermodynamics.