As you drive down the road, you see and hear an approaching ambulance. how is the frequency you hear different from that being produced by the ambulance?

The gravitational force between two objects is 1600 and what will be the gravitational force between the objects if the distance between them doubles?

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.

With physics question #5? for any !