Some Basic Theory

Velocity The displacement divided by the elapsed time v = d / t

Acceleration The change in velocity divided by the elapsed time a = v / t

Newton's First Law of Motion

An object continues in a state of rest or in a state of motion at a constant speed along a straight line, unless compelled to change that state by a net force.

Newton's Second Law of Motion

When a net force F acts on an object m, the acceleration a that results is directly proportional to the net force and has a magnitude that is inversely proportional to the mass. The direction of the acceleration is the same as the direction of the net force. F = m a N (kg m/s2)

Newton's Third Law of Motion

Whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal magnitude on the first body.

Static Frictional Force

The magnitude fs of the frictional force can have any value from zero up to a maximum fsmax , depending on the applied force. u' is the coefficient of static friction and F is the normal force. fs = u' F

Kinetic Frictional Force

The magnitude fk of the kinetic frictional force is given by the relation: fk = u F

where u is the coefficient of kinetic friction and F is the normal force.

The coefficient of friction is at a maximum when the body is static. When the body is set in motion decreases until it reaches a certain level.

Linear Momentum

The linear momentum p of an object is the product of the object's mass m and velocity v : p = m v

Principle of Conservation of Linear Momentum

The total linear momentum of an isolated system remains constant(is conserved). An isolated system is one for which the vector sum of the external forces acting on the system is zero.


A collision is a process involving two objects, each of which exerts a force on the other. Object 1 exerts a force F12 on object 2. Object 2 exerts a force F21 on 1.

m1u1 + m2u2 = m1v1 + m2v2 (elastic collisions)

m1u1 + m2u2 = (m1 + m2)v (inelastic collisions)

Work = Force * Distance = F d = W

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