On sunny days, why do hot-air balloons suddenly rise when they drift over a wide road or a black asphalt parking lot?
What will be an ideal response?
Answer: Air over a warm surface is warmed, becomes less dense, and is buoyed upward. That is why air warmed by a hot black surface rises. Hence a balloon is carried upward by the rising air.
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Characteristics of Waves: What is the frequency of the wave shown in the figure?
A. 0.5 Hz. B. 1 Hz. C. 2 Hz. D. 4 Hz. E. It cannot be determined from the given information.
The solar constant refers to that fact that the Sun's luminosity has remained unchanged in the age of the solar system
Indicate whether the statement is true or false
In a Young's double-slit experiment, what happens to the angular separation between the fringes when the wavelength is increased at the same time that the slit separation is decreased?
a. It increases. b. It decreases. c. It stays the same. d. The relative sizes of the changes need to be known before a definite answer can be given.
A circular loop of wire lies in the plane of the paper. An increasing magnetic field points out of the paper. What is the direction of the induced current in the loop?
A) counter-clockwise then clockwise B) clockwise then counter-clockwise C) clockwise D) counter-clockwise E) There is no current induced in the loop.