The Earth is about ___________ years old by ___________
a. 4 billion years old: radioactive dating
b. 4 million; measuring Earth's orbital period around the Sun
c. 4 billion; measuring Earth's orbital period around the Sun
d. 4 million; radioactive dating
a
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Exhibit 13-1
Two blocks of masses m1 and m2 are connected by a light cord that passes over a pulley of mass M, as shown. Block m2 slides on a frictionless horizontal surface. The blocks and pulley are initially at rest. When m1 is released, the blocks accelerate and the pulley rotates.
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Use this exhibit to answer the following question(s).
Refer to . The total angular momentum of the system of the two blocks and the pulley relative to the axis of rotation of the pulley is
a.
proportional to the radius of the pulley.
b.
proportional to the speed of the blocks.
c.
proportional to the length of the string.
d.
to all of the above.
e.
only to (a) and (b) above.
A plastic rod is rubbed with fur. The rod is then touched to the metal knob of an electroscope. The sign of the charge on the electroscope after contact is ________.
Fill in the blank(s) with the appropriate word(s).
Thin Films: When a beam of light, originally traveling in air, enters a piece of glass having an index of refraction of 3/2, its speed
A. increases by a factor of 3/2. B. is reduced to 2/3 its original value. C. is unaffected.
The ____ of an object depends on the diameter of the object and the distance to the object
a. apparent brightness b. apparent magnitude c. zenith d. angular diameter e. color