Using the free body diagram above for a 1-kg box being pushed across a level floor, describe the change in motion for the box when the applied force is 10N and the frictional force is 8 N.
A)
The box will decelerate at a rate of 8 m/s2
B)
The box will accelerate at a rate of 8 m/s2
Eliminate
The box will decelerate at a rate of 2 m/s2
D)
The box will accelerate at a rate of 2 m/s2

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.