Two particles move about each other in circular orbits under the influence of gravitational forces, with a period τ. their motion is suddenly stopped at a given instant of time, and they are then released and allowed to fall into each other. prove that they collide after a time τ/(4 2).

What is the maximum acceleration of the wing tips, in units of g?

15. give an example for some particles or waves that are moving faster than light in everyday life 16. what is a laser? 17. what is an oscilloscope? 18. what does it means practically that nothing is faster than light in vacuum? 19. what is vacuum?

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.