A rod is pivoted about its center. A 5-N force is applied 4m from the pivot and another 5-N force is applied 2m from the pivot, as shown. The magnitude of the total torque about the pivot (in N. m) is:

Dinate system, and a charge q = - 2.00 nc is placed s2 10 n> c. (a) what is the change in electric potential energy when the dipole moment of a molecule changes its orientation with respect to es from parallel to perpendicular? (b) at what absolute temperature t is the average translational kinetic energy 32 kt of a molecule equal to the change in potential energy calculated in part(: abovethistemperature,thermalagitationprevents the dipoles from aligning with the electric field.) placed in a uniform electric field e with magnitude 1.6 * 6 on the positive x-axis at x = 4.00 cm. (a) if a third charge q3 = +6.00 nc is now placed at the point x = 4.00 cm, y = 3.00 cm, find the x- and y-components of the total force exerted on this charge by the other two. (b) find the magnitude and direction of figure p21.62 ll uu 21.55 . torque on a dipole. an electric dipole with dipole moment ps is in a uniform external electric field es. (a) find the orientations of the dipole for which the torque on the dipole is zero. (b) which of the orientations in part (a) is stable, and which is unstable? (hint: consider a small rotation away from the equi- librium position and see what happens.) (c) show that for the stable orientation in part (b), the dipole’s own electric field tends to oppose the external field. 21.62 ..

Anonzero net force acts on a particle and does work. which one of the following statements is true? the kinetic energy of the particle changes, but the speed of the particle does not change. the kinetic energy of the particle does not change, but the speed of the particle does change. the kinetic energy of the particle changes, but the velocity of the particle does not change. the kinetic energy and the speed of the particle change, but the velocity of the particle does not change. the kinetic energy, speed, and velocity of the particle change.

You are driving to the grocery store at 20 m/s. you are 110m from an intersection when the traffic light turns red. assume that your reaction time is 0.50s and that your car brakes with constant acceleration. how far are you from the intersection when you begin to apply the brakes? what acceleration will bring you to rest right at the intersection? how long does it take you to stop after the light changes? the known values: vi=20m/s xi=110m t=.50s vf=0m/s xf=0m a=?