Q. A projectile is fired horizontally from a gun that is 34.0 m above flat ground, emerging from the gun with a speed of 210 m/s. (a) How long does the projectile remain in the air? (b) At what horizontal distance from the firing point does it strike the ground? (c) What is the magnitude of the vertical component of its velocity as it strikes the ground?
Q. Three equal point charges, each with charge 1.95 , are placed at the vertices of an equilateral triangle whose sides are of length 0.400 . What is the electric potential energy of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)
Use = 8.85×10-12 for the permittivity of free space.