Physics Unit 3

Forces in Equilibrium

Statics and Newtons First Law of Motion learning targets

3-1 I can describe the ideal conditions applied to the study of forces (ignoring friction).

3-2 I can diagram and calculate the horizontal and vertical components and force.

3-3 I can explain contact forces on the atomic scale using the partial model.

3-4 I can mathematically describe frictional forces.

3-5 I can explain and calculate the apparent weight of an object when it's acceleration is zero.

3-6 I can apply Newton's first law of motion to mathematically describe and predict the effects of forces on complex systems of objects.


Component: a part or element of a larger whole, especially a part of a machine or vehicle.

Equilibrium: a state in which opposing forces or influences are balanced.

Free-body diagram: A force diagram is simply a diagram showing all the forces acting on an object, the force's direction and its magnitude. It is a simplification of the picture that shows just the forces.

forces: strength or energy as an attribute of physical action or movement.

Applied forces: An applied force is a force that is applied to an object by a person or another object.

Elastic forces: Elasticity is the ability of a material to return to its original shape after being stretched or compressed. When an elastic material is stretched or compressed, it exerts elastic force.

Electrostatic forces: repulsion & attraction

Friction: the resistance that one surface or object encounters when moving over another.

Gravitational force: a force that attracts any object with mass.

Net force: the overall force acting on an object.

Normal force: the component, perpendicular to the surface of contact, of the contact force exerted on an object.

Tension: the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends.

Nuclear: a strong attractive force between nucleons in the atomic nucleus that holds the nucleus together.

Inertia: a tendency to do nothing or to remain unchanged.

system: a set of connected things or parts forming a complex whole, in particular.

Statics: the study of forces in equilibrium.

Some Things to Remember


Fnet = mass * acceleration