A86.6-kg man is standing on a frictionless ice surface when he throws a 2.40-kg book horizontally at a speed of 10.9 m/s. with what speed does the man move across the ice as a result? give your answer in m/s, and be sure to use three significant figures in your answer.

When the displacement of a mass on a spring is 12a the half of the amplitude, what fraction of the mechanical energy is kinetic energy? at what displacement, as a fraction of a, is the mechanical energy half kinetic and half potential?

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".

An element becomes a positively charged ion when itloses protons. loses electrons. gains electrons. gains neutrons.