A rock is thrown straight up and reaches a maximum height. Which of the following describes the motion at the maximum height?
A. the velocity is zero and the acceleration is zero
B. the velocity is maximum and the acceleration is zero
C. the acceleration is increasing and the velocity is zero
D. the acceleration is not changing and the velocity is zero
D. the acceleration is not changing and the velocity is zero
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Lead melts at 327.44ºC with a heat of fusion of 23.02 kJ/kg. If a 10-kg solid ingot of lead at its saturation temperature is heated in a container at 500ºC, having an average convective heat transfer coefficient of 100 W/m2?K, determine the time to completely melt the ingot. Assume lumped heat capacity.
What will be an ideal response?
Cosmological redshift is the result of
A) the high speeds at which galaxies move within clusters. B) the expansion of the universe. C) very old, red stars in distant galaxies. D) supermassive black holes.
A carpenter is driving a 15.0-g steel nail into a board. His 1.00-kg hammer is moving at 8.50 m/s when it strikes the nail
Half of the kinetic energy of the hammer is transformed into heat in the nail and does not flow out of the nail. What is the increase in temperature of the nail after the three blows that the carpenter needs to drive the nail in completely? The specific heat of steel is 448 J/kg ? K. A) 8.1 K B) 3.6 K C) 1.8 K D) 2.7 K E) 7.7 K
Impedance: If a 1.0-k? resistor is connected in series with a 20-mH inductor, what is the impedance at 1.0 kHz?
A. 0.13 k? B. 1.0 k? C. 1.1 k? D. 0.13 M?