A boy exerts a horizontal force of 119 N on a crate with a mass of 33.2 kg. If the crate doesn't move, what's the magnitude of the static friction force (in N)?
What is the minimum possible value of the coefficient of static friction between the crate and the floor? (Assume the crate remains stationary.)

Sound waves are mechanical waves in which the particles in the medium vibrate ina direction parrallel to the direction of energy transport. what is another name of the type of wave that transfers energy in this way?

As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.

Within a pendulum, as potential energy decreases, energy increases. a. heat b. kinetic c. frictional d. gravitational