In the leftmost photo below, an instructor demonstrates that a standard two-by-four on a curved dish can be rotated by the attractive force of a charged rod. The two-by-four is affected by the charged rod of the same way as:
a. the metal ball in the figure 20-3.
b. the insulating object in the figure at above right.
c. neither of the two; a different mechanism is involved since the two-by-four is so massive.
b
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A negatively-charged particle is slowly moving as it enters a region that has a constant magnetic field. If the velocity of the particle is initially parallel to the magnetic field, what will be the subsequent motion of the particle?
a) It will follow a helical path around the magnetic field lines. b) It will follow a circular path in the plane perpendicular to the magnetic field lines. c) It will follow a straight line path in the same direction as it was initially traveling. d) It will follow a circular path in a plane parallel to the magnetic field lines. e) It is impossible to predict the path the particle will follow.
When air resistance is a factor, maximum range is achieved when the projection angle is
A) less than 45.° B) 45.° C) greater than 45.° but not 90.° D) 90.°
A 10-kg block on a rough horizontal surface is attached to a light spring (force constant = 1.4 kN/m). The block is pulled 8.0 cm to the right from its equilibrium position and released from rest. The frictional force between the block and surface has a magnitude of 30 N. What is the kinetic energy of the block as it passes through its equilibrium position?
a. 4.5 J b. 2.1 J c. 6.9 J d. 6.6 J e. 4.9 J
In China tonight the Moon phase is first quarter, so tonight for you the Moon phase is ______
a. waxing gibbous b. first quarter c. new d. waxing crescent