What must exist for electric charges to flow?

Lars is jogging besides the railroad tracks at a speed of 2.00m/s when he hears a train whistles behind him at a frequency of 2115Hz. if the actual frequency of the train whistle is 2000 Hz, how fast is the train moving

True or false kinetic energy is energy that moves matter

Why are some materials magnetic and not others?

What is a statement that's summarizes a pattern found in nature

A referee will toss up the ball between to opponents. what is this called

What type of invention is created to increase profits

Which of the following is a simple sugar? lactase lactose sucrose glucose

Which best describes the current atomic theory? A since it is only a theory it shouldn't be used in practice B it has not been tested enough to be useful for developing technology C it is the most powerful explanation scientist have to offer at this

What are the factors affecting elasticity?

The name of the group of science that deals with earth and its neighbors in space is called