Name all of the four levels of time humans are living in today

What is the focal length of a concave mirror that magnifies, by a factor of + 3.2 an object that is placed 30 cm from the mirror?

Which explanation best describes the development of a wave?

A lightbulb glows brightly when it is connected across a certain battery. The battery will maintain a constant potential difference even as its output current increases.

A 0.8 m length of wire is formed into a single turn, square loop in which there is a current of 12 A. The loop is placed in magnetic field of 0.12 T, which is perpendicular to a normal to the loop plane.

A football kicker kicks a ball with a mass of. 42 kg. The average acceleration of the football was 14.8 m/s squared. How much force did the kicker supply to the football?

What is the energy source that heats a contracting protostar?

What unit is kg divided by m/s^2

If the energy stored in the fully charged battery is used to lift the battery with 100-percent efficiency, what height is attained? Assume that the acceleration due to gravity is 9.8 m/s2m/s2 and is constant with height

How does the mass of an astronaut change when she travels from earth to the moon? how does her weight change?

If an object has a mass of 20 grams and a volume of 40 cm3, what is its density in g/cm3?