A plastic ball in a liquid is acted upon by its weight and by a buoyant force. The weight of the ball is 2.6 N. The buoyant force has a magnitude of 4.4 N and acts vertically upward. At a given instant, the ball has zero velocity. At that instant, an external force acting on the ball imparts an acceleration of 3.0 m/s2 in the downward direction of the ball. The external force, including direction, is closest to:

How would you place two electrons on a sphere of radius r so that the electrostatic potential energy is minimized. how would you place three electrons to solve the same problem.

Awater-filled u-tube manometer is used to measure the pressure inside a tank that contains air. the water level in the u-tube on the side that connects to the tank is 5 ft above the base of the tank. the water level in the other side of the u-tube (which is open to the atmosphere) is 2 ft above the base. determine the pressure within the tank.

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.