What is the best thermal insulator? aluminum copper steel or glass

What is the acceleration of a spaceship that is initially at rest and then speeds up to 220 m/s in 20 seconds

Achlorine atom has 17 protons and 18 neutrons. what is its mass number? what is its atomic number?

Ametal ring 4.20 cm in diameter is placed between the north and south poles of large magnets with the plane of its area perpendicular to the magnetic field. these magnets produce an initial uniform field of 1.12 t between them but are gradually pulled apart, causing this field to remain uniform but decrease steadily at 0.240 t/s . (a) what is the magnitude of the electric field induced in the ring? (b) in which direction (clockwise or counterclockwise) does the current flow as viewed by someone on the south pole of the magnet?