A 20.0 kg box slides up a 12.0 m long incline at an angle of 30.0 degrees with the horizontal. A force of 150 N is applied to the box to pull it up the incline. The applied force makes an angle of 0.00 degrees to the incline. If the incline has a coefficient of kinetic friction of 0.100, then the increase in the kinetic energy of the box is
A. 330 J.
B. 390 J.
C. 420 J.
D. 481 J.
E. 597 J.
C. 420 J.
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Suppose that several projectiles are fired upward. Which one will be in the air longest? (R is range, h is highest elevation, and t is time of flight.)
A) The one with the farthest range, R B) The one with the highest maximum elevation, h C) The one for which the product of (R)(t)(h) is maximum D) The one with the greatest initial velocity E) The one with the minimum elevation, h
Specific Heat: A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper, with the aluminum and the copper in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium?
A. the copper B. the aluminum C. Neither one; both of them experience the same size temperature change. D. It is impossible to tell without knowing the masses. E. It is impossible to tell without knowing the volumes.
A 4.00 kg solid sphere (I = 2/5 
) is spinning with an angular velocity of 23.0 rad/s. The diameter of the sphere is 20.0 cm. The angular kinetic energy of the spinning sphere is
A. 3.02 J. B. 3.52 J. C. 3.75 J. D. 4.02 J. E. 4.23 J.
Resistors in Combination: What is the equivalent resistance of the circuit shown in the figure? The battery is ideal and all resistances are accurate to 3 significant figures.
A. 950 ? B. 450 ? C. 392 ? D. 257 ?