Download Energy is the ability to do work. Work is actually a transfer of energy

15.1 Energy and Its Forms
Energy is the ability to do work.
Work is actually a transfer of energy.
When work is done to an object, energy is transferred to
that object.
Energy is measured in joules (J) – just like work.
Energy can take several different forms.
Mechanical Energy is the sum of potential and kinetic
energy.
Thermal Energy is the sum of potential and kinetic energy of
all the particles in an object. Measured as temperature.
Chemical Energy is stored energy in chemical bonds.
Electrical Energy is the transfer of electric charges.
Electromagnetic Energy is energy that travels through space
as waves. Sunlight, radio-waves and X-rays
Nuclear Energy is the stored energy that holds together the
nucleus of an atom.
Nuclear fission is a process that splits the nucleus apart to
release nuclear energy.
2 types of Mechanical Energy:
kinetic energy and potential energy
Kinetic Energy (KE) is the energy of motion.
All moving objects have KE.
The kinetic energy depends on an object’s mass and speed.
The mathematical equation for KE: KE = ½ mv2
More mass  more KE
Greater speed  greater kinetic energy
KE is more dependant on speed than mass (speed is squared)
Potential Energy (PE) is energy that is stored in an object as
a result of its position or shape.
2 types of potential energy:
1. Gravitational Potential Energy (PEg) An object gains
gravitational potential energy when it is raised to a greater
height.
The mathematical equation for PEg: PEg = m ag h
2. Elastic Potential Energy (PEe). An object gains elastic
potential energy when it is stretched or is pressed together.
For example, stretching a rubber band or pressing a spring
gives the object elastic potential energy.
Calculating Kinetic Energy A 0.10-kilogram bird is flying at
a constant speed of 8.0 m/s. What is the bird’s kinetic energy?
Givens
What information are you given?
Mass, m = 0.10 kg
Speed, v = 8.0 m/s
What unknown are you trying to calculate?
Kinetic energy of the bird, KE =?
Plan and Solve
What equation contains the given quantities and the unknown?
KE = ½ mv2
Substitute the known values in the formula for KE.
KE = ½ (0.10 kg)(8.0 m/s)2 = ½ (0.10 kg)(64 m2/s2)
KE = 3.2 kg m2/s2 = 3.2 N m = 3.2 J
Look Back and Check
Is your answer reasonable? Yes, small bird (mass) = small KE