At what rate is the gravitational force on a 2.0-kg projectile doing work at an instant when the velocity of the projectile is 4.0 m/s directed 30° above the horizontal?
a. +39 W
b. -78 W
c. -39 W
d. +78 W
e. +25 W
C
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Alien astronomers are using the radial-velocity method to look for planets around our Sun. Which planet are they most likely to detect first?
A. Jupiter B. Neptune C. Mercury D. Earth
A straw is used for a pea shooter. When you blow through the straw the speed of the emerging pea will be greater if the straw is
A) cut in half. B) full length. C) either cut in half or full length.
When the first law of thermodynamics, Q = ?u + W, is applied to an ideal gas that is taken through an adiabatic process,
A) ?u = 0. B) W = 0. C) Q = 0. D) it is not true that ?u = 0 or W = 0 or Q = 0.
Compare two collisions that are perfectly inelastic. In case (A) a car traveling with speed V collides head-on with a sports car having half the mass and traveling in the opposite direction with twice the speed. In case (B) an identical car traveling with the same speed V collides head-on with a light truck having twice the mass and traveling in the opposite direction with half the speed