According to the doppler effect, the sound of a police car siren (a. quieter b. louder) (a. higher b. lower) pitched as it approaches the observer.

1400 kg car has a speed of 27 m/s. if it takes 7 s to stop the car, what is the impulse and the average force acting on the car?

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Part 1: a magnetic levitation or maglev train rides rails without touching them. explain how this works using your data. include the appropriate magnet drawing in your answer. part 2: two objects are near a bar magnet. one is about 1 cm away, while the other is 6 cm away. compare and contrast the magnetic force that affects each object. use your data to answer the question