Which one of the following substances can be separated into several different elements?

A: Air

B: Iron

C: hydrogen

D: nickel

The echo of your footsteps returns in 0.50 second. How long is the corridor in which you are walking? (Assume the speed of sound for 0°C.)

According to the nebular model, how were planets formed?

A sample of blood is placed in a centrifuge of radius 12.0 cm. The mass of a red blood cell is 3.0 ✕ 10^-16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0 ✕ 10^-11 N.

A lowly high diver pushes off horizontally with a speed of 2.82 m/s from the edge of a platform that is 10.0 m above the surface of the water. (a) At what horizontal distance from the edge of the platform is the diver 0.

An instructor furiously cranks an electric generator to simultaneously power 5 electric light bulbs. Each 5.4 V bulb is drawing 0.14 A of current.

Which of the following statements about electrons is not true? A) Electrons orbit the nucleus rather like planets orbiting the Sun. B) Within an atom, an electron can have only particular energies.

In longitude waves, the medium moves parallel to the direction of energy transport

Thomsonâs experiment is credited with the discovery of which particle?

When you drop a pebble from height h, it reaches the ground with kinetic energy k if there is no air resistance. from what height should you drop it so it will reach the ground with twice as much kinetic energy?

Explain two ways that technology has had a positive impact on the environment and two ways that it has had a negative impact on the environment.