5 terms

# Physics

#### Terms in this set (...)

Newton's Laws
Newton's laws of motion are three physical laws that, together, laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces. They have been expressed in several different ways, over nearly three centuries, and can be summarized as follows.

- First Law: When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity unless acted upon by a net force.

- Second Law: In an inertial reference frame, the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration vector a of the object: F = ma.

- Third Law: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

- Explain in your own words
- Provide 1 - 2 examples
Momentum
the product of the mass and velocity of an object. For example, a heavy truck moving rapidly has a large momentum—it takes a large or prolonged force to get the truck up to this speed, and it takes a large or prolonged force to bring it to a stop afterward. If the truck were lighter or moving more slowly, then it would have less momentum.

- Explain in your own words
- Provide 1 - 2 examples
Quantum Mechanics
Quantum mechanics is the branch of physics relating to the very small. It results in what may appear to be some very strange conclusions about the physical world. At the scale of atoms and electrons, many of the equations of classical mechanics, which describe how things move at everyday sizes and speeds, cease to be useful. In classical mechanics, objects exist in a specific place at a specific time. However, in quantum mechanics, objects instead exist in a haze of probability; they have a certain chance of being at point A, another chance of being at point B and so on.

- Explain in your own words
- Provide 1 - 2 examples
Critical Mass
The term "critical mass" seems to have first appeared in nuclear physics. In this discipline, "critical mass" is the minimum amount of a given fissile material necessary to achieve a self-sustaining fission chain reaction. The term, however, is now used as a much broader construct. In astrophysics, for example, critical mass is a concept used to designate any mass that when exceeded causes something to happen. The concept of critical mass exists outside of physics and can easily be thought of as a tipping point. A Tipping Point, according to noted author Malcolm Gladwell in The Tipping Point: How Little Things Can Make a Big Difference, "is the moment of critical mass, the threshold, the boiling point."

- Explain in your own words
- Provide 1 - 2 examples
Equilibrium
Equilibrium is a balance between one or more opposing forces. As you can imagine, different types of equilibrium exist. Static equilibrium is when a system is at rest. Dynamic equilibrium is when two or more forces are equally matched.

- Explain in your own words
- Provide 1 - 2 examples
STUDY GUIDE