A wheel starts from rest and rotates with a constant angular acceleration about a fixed axis. It completes the first revolution 6.0 s after it started. How long after it started will the wheel complete the second revolution?
A. 9.9 s
B. 7.8 s
C. 8.5 s
D. 9.2 s
E. 6.4 s
Answer: C
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Suppose a 1.0-kg object traveling rightward at 1.0 m/s hits a 3.0 kg object at rest. Afterward, we observe the lighter object to move leftward with a speed of 0.75 m/s. What impulse did the collision interaction give the smaller object at the expense of the larger?
A. None; the larger object was at rest and so had no momentum to give the smaller object. B. None; the smaller object gave an impulse to larger, not the other way around. C. 0.75 kg·m/s leftward. D. 1.0 kg·m/s leftward. E. 1.75 kg·m/s leftward.
A string of length L with fixed ends is made to go into standing wave patterns. What is the longest wavelength associated with all possible standing wave patterns in this situation?
a. L/4 b. L/2 c. L d. 2L
Two 1.5 m-square and parallel flat plates are 30 cm apart. Plate A1 is maintained at a temperature of 1100 K and A2 at 500 K. The emissivities of the plates are 0.5 and 0.8, respectively. Considering the surroundings black at 0 K and including multiple inter-reflections, determine (a) the net radiant exchange between the plates and (b) the heat input required by surface A1 to maintain its temperature. The outer-facing surfaces of the plates are adiabatic.
GIVEN
• Two square parallel flat plates, 30 cm apart
• Temperature of A1 (T1) = 1100 K
• Temperature of A2 (T2) = 500 K
• Emittances: ?1 = 0.5 ?2 = 0.8
• Surroundings are black at (T3) = 0 K
FIND
Including multiple inter-reflections, determine:
(a) The net radiant exchange (q1–2)
(b) The heat input at surface A1 (q1) required to maintain its temperature
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/(m2 K4)
Which of the above sections of this molecule would be considered an unsaturated portion of the molecule?
A) a B) b C) c D) a and b E) all of the above