b. The trains have a top speed in a straight line of 20ms-1. In order to ensure that passengers are comfortable, the acceleration and deceleration of the trains are limited to 3ms-2. i. The route is counterclockwise starting from stop A and remains stationary at each stop for 2 minutes. Assuming that the train's acceleration/deceleration is constant, calculate the time taken to reach each stop - including the time taken to go back to stop A. Marks -5 a HT I 0.5km KE 0.5km 10.5km 0.75km ° 0.4km 2km R=75m 0.5km 0.5km

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.

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Acar drives toward the right over the top of a hill, as shown below. which arrow represents the centripetal acceleration? w x y z