NOTES ON KINETIC ENERGY AND WORK-ENERGY THEOREM
K=
12 mv Kinetic Energy 2
wnet = K f K i = K Work-Energy Theorem
a) Kinetic energy is energy associated with the motion of a particle. b) The SI unit of KE is the joule (J). c) The Work-Energy Theorem is val
MOMENT OF INERTIA
I = mi ri 2 Moment of Inertia
The rotational KE can now be expressed in terms of the Moment of Inertia:
KR =
12 I Rotational Kinetic Energy 2
a) The SI unit of I is the kg m2 b) I is the rotational analog of mass.
KT = 1 mV 2 Translation
Law of Gravitation In 1687 Isaac Newton published his Law of Gravitation which is stated mathematically in the following form:
Fg =
Gm1m2 r2
Law of Gravitation
G = 6.672 1011
Fg
Nm 2 kg 2
(Gravitation Constant)
m2 Fg R2 m2
r Fg m1 R1 m1 Fg r
Although the
FRICTION
One type of force that we have not yet considered is that due to friction. The following situations demonstrate the two types of frictional forces we will be considering static and kinetic frictional forces.
no applied force; object remains at re
Collisions
Def: A collision is an event in which 2 or more objects interact for a very short period of time. During this time, the external forces (if any) on the system are much smaller than the internal impulsive forces between the objects and thus can
Spring Force
How do we calculate the work done by a non-constant force? Before we answer the question lets consider the spring force which is an example of a nonconstant force. Consider the following Spring-Mass System.
a) Note that the spring force Fs is
SCALAR (DOT) PRODUCT Before we define work in physics we need to first define the scalar (dot) product between two vectors. The reason for this is because we will define work in terms of the scalar (dot) product between the force vector and displacement v
POTENTIAL ENERGY
Often the work done on a system of two or more objects does not change the kinetic energy of the system but instead it is stored as a new type of energy called POTENTIAL ENERGY. To demonstrate this new type of energy lets consider the fol
VECTORS DEF: A vector is a quantity that has both magnitude and direction. DEF: A scalar is a quantity that has magnitude but NO direction. Ex. Vectors Force Velocity Displacement Momentum Ex. Scalars Temperature Time Mass Speed
Vector Notation A Boldface
OBJECTS IN FREE-FALL Def: An object in free-fall is any object that is moving freely under the influence of gravity alone, regardless of its initial position and velocity.
g
9.8 m / s 2 Acceleration of Gravity
Near EarthsSurface The direction of g is towa
NEWTONS LAWS OF MOTION Newtons Laws are the foundation of Classical (Newtonian) Mechanics. They were published by Isaac Newton in 1687 along with the law of gravitation in the Principia. They have far reaching applications/implications in every branch of