How do we know the universe is a closed system?

What do astronomers expect will eventually happen to the Milky Way galaxy?

What is the information gathered in an investigation is called

Where is oxygen absorbed by red blood cells? A Diaphragm B Nose C Alveoli D Trachea

An electron is said to have a positive/negative/neutral charge

Earth's magnetic field can make a magnet out of an iron bar by causing the magnetic domains to

The potential difference between the terminal of an electrical heater is 60v when it draw a current 4A fron the source. What current will the heater draw if the potential difference is increased to 120v?

Which answer choice best explains why nuclear reactions release more energy than chemical reactions? Electrostatic forces of repulsion are thousands of times stronger than gravitational forces.

A train's mass is 18181.81 kg. What is its weight?

a 3.0m long frictionless pendulum swings with a maximum angluar displacement of 10 degree from the vertical. at its lowest position the kinetic energy of the pendulum is 20.0j what is the potential energy of the pendulum when the kientic energy is 5.

How are hypotheses and theories related to each other?