A 3.0-kg mass is dropped from the edge of a 50-m tall building with an initial speed of zero. The mass strikes the ground with a downward velocity of 25 m/s. Find the change in mechanical energy of the mass caused by air resistance between the point where it is dropped and the point where it strikes the ground
a. ?0.46 kJ
b. ?0.53 kJ
c. ?0.61 kJ
d. ?0.38 kJ
e. ?0.81 kJ
b
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While a stone is falling [neglecting air resistance],
A) its speed is changing. B) the direction of its velocity is downward. C) it is accelerated. D) All of the above. E) None of the above.
A 6.0-?F capacitor charged to 50 V and a 4.0-?F capacitor charged to 34 V are connected to each other, with the two positive plates connected and the two negative plates connected. What is the total energy stored in the 6.0-?F capacitor at equilibrium?
A. 6.1 mJ B. 5.7 mJ C. 6.6 mJ D. 7.0 mJ E. 3.8 mJ
The United States today gets nearly all of its energy from three energy resources. Which one of the following is not one of these three?
A) natural gas B) coal C) oil--i.e., petroleum D) nuclear
For the titanium with a 2 % pre-strain in Figure 7.9, what grain size would result in a yield stress of 1000 MPa? You can use the results of Example Problem 7.2 to determine your answer.
What will be an ideal response?