A 60Kg man standing on stationary 40kg boat throws a 0.2kg ball with a velocity of 4m/s. Assuming that there's no friction between the man and the boat, what's the speed of the boat after the man throws the ball?

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Suppose a wire with a current is pushed upward by a magnetic field. how would the wire move if the direction of the current reversed? explain your answer.

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.