What is ultrasound? what is its use in industry? why can't we use longer wavelengths for such uses?

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

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant

Why is it important always to use horizontal bars in unit fractions when performing unit conversions?