A certain radioactive substance has a half life of one hour. if you start with 1g of the material at noon how much will be left at 3:00 PM?

Light from a sodium lamp passes through a diffraction grating having 1000 slits per millimeter. The interference pattern is viewed on a screen of 1.00m behind the grating. Two bright yellow fringes are visible 72.88cm and 73.

A box with a total surface area of 1.88 m^2 and a wall thickness of 2.44 cm is made of an insulating material. A 14.1 W electric heater inside the box maintains the inside temperature at 18.6 ◦C above the outside temperature.

Create a sketch that shows the particles of matter in two substances that differ in density. Label the sketch to show which substance has greater density.

Which of the following is not an SI unit?

Lowest frequency of wave

calculate the force exerted on a rocket given that the propelling gases are expelled at a rate of 1500 kg/s with a speed of 4.0x10^4 (at the moment of take off)

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?