Examples of force in the following topics:

 For example, when determining what happens when two forces act on the same object, it is necessary to know both the magnitude and the direction of both forces to calculate the result.
 In this simple onedimensional example, without knowing the direction of the forces it is impossible to decide whether the net force is the result of adding the two force magnitudes or subtracting one from the other.
 Associating forces with vectors avoids such problems.
 Ideally, these diagrams are drawn with the angles and relative magnitudes of the force vectors preserved so that graphical vector addition can be done to determine the net force.
 Forces are resolved and added together to determine their magnitudes and the net force.

 Recall that the force of friction depends on both the coefficient of friction and the normal force.
 As always, the frictional force resists motion.
 If the frictional force is equal to the gravitational force the block will not slide down the incline.
 If the maximum frictional force is greater than the force of gravity, the sum of the forces is still 0.
 The force of friction can never exceed the other forces acting on it.

 The normal force comes about when an object contacts a surface; the resulting force is always perpendicular to the surface of contact.
 The person remains still because the forces due to weight and the normal force create a net force of zero on the person.
 When the elevator goes up, the normal force is actually greater than the force due to gravity.
 The second is the normal force.
 The following forces act on the mass: the weight of the mass ($m \cdot g$),the force due to friction ($F_r$),and the normal force ($F_n$).

 A force which causes motion in a curved path is called a centripetal force (uniform circular motion is an example of centripetal force).
 A force that causes motion in a curved path is called a centripetal force.
 Uniform circular motion is an example of centripetal force in action.
 Centripetal force can also be expressed in terms of angular velocity.
 The equation for centripetal force using angular velocity is:

 Impulse, or change in momentum, equals the average net external force multiplied by the time this force acts.
 where F is the net force on the system, and Δt is the duration of the force.
 change in momentum equals the average net external force multiplied by the time this force acts.
 Forces are usually not constant.
 A graph of force versus time with time along the xaxis and force along the yaxis for an actual force and an equivalent effective force.

 Nuclear force is the force that is responsible for binding of protons and neutrons into atomic nuclei.
 The nuclear force is the force between two or more component parts of an atomic nuclei.
 The nuclear force is now understood as a residual effect of an even more powerful "strong force" or strong interaction.
 The nuclear forces arising between nucleons are now seen as analogous to the forces in chemistry between neutral atoms or molecules (called London forces).
 These nuclear forces are very weak compared to direct gluon forces ("color forces" or "strong forces") inside nucleons, and the nuclear forces extend over only a few nuclear diameters, falling exponentially with distance.

 Net force affects the motion, postion and/or shape of objects (some important and commonly used forces are friction, drag and deformation).
 Another interesting force in everyday life is the force of drag on an object when it is moving in a fluid (either gas or liquid).
 Like friction, the force of drag is a force that resists motion.
 We see an illustrated example of drag force in.
 It omits the two vertical forces—the weight of the barge and the buoyant force of the water supporting it cancel and are not shown.

 A simple machine has an applied force that works against a load force.
 The ratio of the output force to the input force is the mechanical advantage of the machine.
 They use only three forces: the input force, output force, and force on the pivot.
 The amount of force produced by a machine can not be greater than the amount of force put into it.
 Develop an understanding of how a machine applies force to work against a load force

 Net external forces (that are nonzero) change the total momentum of the system, while internal forces do not.
 Forces external to the system may change the total momentum when their sum is not 0, but internal forces, regardless of the nature of the forces, will not contribute to the change in the total momentum.
 External forces: forces caused by external agent outside of the system.
 There are mainly three kinds of forces: Gravity, normal force (between ice & pucks), and frictional forces during the collision between the pucks
 Since all the external forces cancel out with each other, there are no net external forces.

 The superposition principle (superposition property) states that for all linear forces the total force is a vector sum of individual forces.
 For Coulomb's law, the stimuli are forces.
 Therefore, the principle suggests that total force is a vector sum of individual forces.
 Of course, our discussion of superposition of forces applies to any types (or combinations) of forces.
 Total force, affecting the motion of the charge, will be the vector sum of the two forces.