An atom must emit a photon when a(n) ____
a. electron moves from a lower to a higher energy level
b. proton moves from a lower to a higher energy level
c. proton moves from a higher to a lower energy level
d. electron moves from a higher to a lower energy level
e. atom becomes ionized
d
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Neutrons:
A) have double the mass of protons. B) are atomic particles with no charge. C) when equal in number form isotopes. D) exist independently and unattached to atoms.
Does a magnetic field exert a force on a stationary object?
1.yes 2.no
A simple pendulum has a mass of 0.50 kg and a length of 1.0 m. It is displaced through an angle of 30° and then released. After a time, the maximum angle of swing is only 10°. How much energy has been lost to friction?
a. 2.0 J c. 0.66 J b. 1.6 J d. 0.58 J
The airspeed of an airplane is 100 km/h. When it is caught in a 100-km/h right-angled crosswind, its speed across the ground below is about
1) 0 km/h. 2) 100 km/h. 3) 140 km/h. 4) 200 km/h. 5) more than 200 km/h. If the airplane changes direction and flies at 60 degrees to the wind, its ground speed will 6) decrease. 7) remain the same. 8) increase.