A balloon rubbed against denim gains a charge of -3.0 uC. What is the electric force between the balloon and the denim when the two are separated by a distance of 6.0 cm? (As- sume that the charges are located at a point.) The value of the Coulomb constant is 8.98755 x 10^9 N •m²/C^2. Include direction of the force.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".