Aparticle of mass m and charge +q is confined to move in a horizontal rod situated a distance d above two charges of +q that are fixed a distance 2d apart. the line connecting the two +q charges is parallel to the rod. the charge +q is fixed to move between and above the two charges. what is u(x) for this particle where x is the distance along the rod from a point equidistant and above the +q charges? find the frequency of small oscillations from the equilibrium

Aballoon is rising vertically upwards at a velocity of 10m/s. when it is at a height of 45m from the ground, a parachute bails out from it. after 3s he opens his parachute and decelerates ata a constant rate 5m/s.when. (a) what was the height of the parachutist above the ground when he opened his parachute? (b)how far is the parachutist from the balloon at t=3s? (c)with what velocity does the parachutist hit the ground? (d)after how long does the parachutist hit the ground after his exist from the balloon?