If a force on an object is aimed in the direction of the object's velocity, the force does
a. no work c. negative work
b. positive work d. any of the above
B
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According to the Bohr model, an electron in an excited state of hydrogen can emit
A) at most a single photon until the atom re-excites. B) several photons in a series of transitions to a lower state. C) a continuous stream of light. D) none of the above
Thermodynamic Processes: The figure shows a pV diagram for 8.3 g of ideal nitrogen gas N2 in a sealed container. The temperature of state 1 is 59°C, the atomic mass of the nitrogen atom is 14 g/mol, and R = 8.31 J/mol ? K. What are (a) pressure p1 and (b) temperature T2?
A. (a) 81 atm, (b) 660°C B. (a) 14 atm, (b) 660°C C. (a) 81 atm, (b) 120°C D. (a) 14 atm, (b) 120°C
A pirate demands that his 75kg prisoner “walk the plank”. The prisoner walks out on an 8.0m long, 50kg horizontal board that juts out from the side of the pirate ship. If he walks out 7.5m from the place where the board is connected to the ship’s side, what is the net torque applied to the board?
A. 5500 Nm B. 7500Nm C. 0 Nm D. 2000 Nm E. Cannot determine
A lens is used as a magnifier. Which of the following statements is incorrect?
a. The focal length of the lens must be negative. b. The magnification is greatest when the eye focuses at the near point. c. The refractive power of the lens is positive. d. The lens is convex.