A car of mass 1.15×10^3kg is stalled on a horizontal road. You and your friends give the car a constant, forward, horizontal push. There is friction between the car and the road. The combined force that you and your friends exert has magnitude 8.00×10^2N and starting from rest the car reaches a speed of 1.40 m/s. Find the magnitude of the constant friction force that acts on the car.

Ahowler monkey is the loudest land animal and, under some circumstances, can be heard up to a distance of 4.6 km. assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10-12 w/m2. what is the acoustic power emitted by the howler

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?

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.