What is the force of a 7000g block sliding down a hill at 4 m/s^

Three point charges, two positive and one negative, each having a magnitude of 20 μc are placed at the vertices of an equilateral triangle (30 cm on a side). what is the magnitude of the electrostatic force on the negative charge

The softest and hardest minerals are: softest hardest

If you place a magnet under a clear dish, and sprinkle iron fillings over it, above what part of the magnet will most of the fillings gather