Aspaceship at rest relative to a nearby star in interplanetary space has a total mass of 2.60 ✕ 104 kg. its engines fire at t = 0, steadily burning fuel at 76.0 kg/s with an exhaust speed of 4.50 ✕ 103 m/s. calculate the spaceship's acceleration at t = 0, mass at t = 115 s, acceleration at t = 115 s, and speed at t = 115 s, relative to the same nearby star.

(a) acceleration at t = 0 (enter the magnitude. enter your answer in m/s2.)
(b) mass at t = 115 s (enter your answer in kg.)
(c) acceleration at t = 115 s (enter the magnitude. enter your answer in m/s2.)
(d) speed at t = 115 s (enter your answer in m/s.)

Look at the potential energy diagram for a chemical reaction. which statement correctly describes the energy changes that occur in the forward reaction?

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

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.