Tom has a mass of 73 . 9 kg and sally has a mass of 59 . 8 kg. tom and sally are standing 27 . 9 m apart on a massless dance floor. sally looks up and she sees tom. she feels an attraction. if the attraction is gravitation, find its mag- nitude. assume both can be replaced by spherical masses and that the gravitational constant is 6 . 67259 × 10 ^− 11 n · m^ 2 / kg^ 2 . answer in units of n.

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".