A1200 kg frictionless roller coaster starts from rest at a height of 19 m. what is its kinetic energy when it goes over hill that is 13 m high?

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

Ahair dryer is basically a duct in which a few layers of electric resistors are placed. a small fan pulls the air in and forces it through the resistors where it is heated. air enters a 1200 w hair dryer at 100 kpa and 22°c and leaves at 47°c. the cross-sectional area of the hair dryer at the exit is 60 cm2. neglecting the power consumed by the fan and the heat losses through the walls of the hair dryer, determine (a) the volume flow rate of air at the inlet and (b) the velocity of the air at the exit.

If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?