When a 45-kg person steps on a scale in an elevator, the scale reads a steady 410 N. Which of the following statements must be true? (There could be more than one correct choice.)
A) The elevator is accelerating upward at a constant rate.
B) The elevator is accelerating downward at a constant rate.
C) The elevator is moving upward at a constant rate.
D) From the given information, we cannot tell if the elevator is moving up or down.
B, D
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An astronaut lands on a previously unknown planet of radius 2350. km and she measures the acceleration of gravity to be 3.20 m/s2
(a) What is the mass of this new planet? (b) What does the astronaut weigh on this new planet if she weighs 384. N on Earth?
A parallel-plate capacitor has dimensions 4.3 cm × 4.6 cm. The plates are separated by a 1.0-mm thickness of paper (dielectric constant ? = 3.7). What is the charge that can be stored on this capacitor, when connected to a 1.2-V battery? (?0 = 8.85 × 10^?12 C2/N?m2)
a. 2.0 × 10^?12 C b. 3.9 × 10^?12 C c. 3.9 × 10^?11 C d. 7.8 × 10^?11 C e. 6.8 × 10^?11 C
What is the minimum thickness of a soap bubble film with refractive index 1.38 that results in a constructive interference in the reflected light if this film is illuminated by a beam of light of wavelength 610 nm?
A) 444 nm B) 222 nm C) 555 nm D) 333 nm E) 111 nm
In order for two objects to have the same temperature, they must
a. be in thermal equilibrium. b. be in thermal contact with each other. c. have the same relative "hotness" or "coldness" when touched. d. have all of the properties listed above. e. have only properties (b) and (c) above.