Help with science Anayliss Questions ASAP

(Plz answer correctly

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

Afigure skater is rotating at a rate of 200 revolutions per minute. what is the angular speed, in units of rad/s? 20.9 12000 200 3.33

You hang a book bag on a spring scale and place the bag on a platform scale so that the platform scale reads 23.7n and the spring scale reads 13.8n. what is the magnitude of the force that earth exerts on the bag?