The main purpose of the turbine in the turbojet engine is to
a. drive the compressor.
b. reduce the temperature of the exhaust gas.
c. increase the velocity of the exhaust gases.
d. compress the air. ~it is not d.

Modify the equation fδt=δ (mv) to find the force of friction.

Astone dropped into a well is heard to strike the water after 8seconds. find the depth of the well if the velocity of sound is 350m/s

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.