Download Study Sheet for Physics Energy is the ability to cause change or do

Study Sheet for Physics
Energy is the ability to cause change or do work
Energy is either potential energy or kinetic energy.
Types of Potential Energy (stored energy):
Gravitational – due to position. Depends on height and mass.
Elastic – energy stored in objects that are compressed or stretched.
Chemical – energy stored in chemical bonds. Released when reactions occur.
Types of Kinetic Energy (Energy in motion)
Mechanical Energy The sum of potential and kinetic energy in a system
Sound Energy Energy caused by vibrating molecules. Needs matter to travel.
Thermal Energy Energy of moving molecules in a substance
Electric Energy Energy of an electric current(electrons jumping from atom to atom)
Radiant Energy Energy that is in electromagnetic waves. Can travel in a vacuum.
Nuclear Energy Energy in an atom’s nucleus. Is released when the nuclei go together (fusion) or when one breaks apart
(fission).
The law of conservation of energy says that energy cannot be created or destroyed. Energy, therefore, has to be
conserved. This means that it simply changes from one form of energy to another.
For instance a cell phone sends and receives radiant energy using microwaves. When you are listening to someone on a
cell phone, that cell phone is transforming radiant energy into electric energy and then into sound energy. When you are
speaking into a cell phone, it is transforming sound energy into electric energy and then into radiant energy.
Friction often transforms mechanical energy into thermal energy.
A wave is a disturbance that transfers energy from place to place without transferring the matter. Mechanical waves
require matter to travel on, but electromagnetic waves do not. EM waves can travel through a vacuum.
The electromagnetic spectrum is based on wavelengths.
The longest wavelengths are radio waves and the
shortest wavelengths are gamma rays. The wavelength
relates to energy with the shortest having the most.
Visible light goes in order roygbiv with red being the
longest wavelength and violet being the shortest.
Waves can have different types of motion.
A transverse wave is a wave where the disturbance is perpendicular to the direction the wave travels.
A longitudinal wave makes the particles move back and forth like the motion of a slinky being pushed.
Frequency is the number of waves that pass a certain point in a given amount of time. The higher the frequency, the
shorter the wavelength and the greater the energy of the wave. This wave would also have a high pitch if it was a sound
wave.
A force is a push or a pull that is measured on a spring scale in newtons. A contact force is a push or a pull on one object
by another that is touching it. The types of contact forces are:
Friction – a force that resists the motion of two surfaces that are touching.
Applied – a force that is given to an object by a person or another object.
Normal – a force that is exerted on an object by another stable object.
Spring – a force that is exerted by a stretched or a compressed spring to an object that is attached to it.
Tension – A force that is exerted by a rope, string, etc that is stretched tight and equal in force at both ends
Air resistance – An upwards force applied to falling object. It is a type of friction.
Non-contact forces are forces that are in effect even though the objects are not in contact. Examples are
Gravity- A force pulling object down toward earth. Magnetic – a force
Remember that weight and mass are different. Mass is not affected by gravity but weight is a measure of gravity.
Magnetic force – A force that is a force of attraction with poles.
Electrical force – A force of attraction with positive and negative.
A balanced force is when the forces acting on an object combine and form a net force of zero.
An unbalanced force is when the forces acting on an object combine and form a net force that is not zero.
Motion is caused where there are unbalanced forces.
If the net force is zero, then there is no motion.
If the force is unbalanced, then the motion will be in the direction of the stronger force.
Work is the transfer of energy to an object by a force that makes an object move in the direction of the force.
Work is only being done while the force is applied to the object.
The formula for work is force x distance = work.
Work is measured in Nm. (newton meters)
A simple machine is something that makes work easier.
The following are the simple machines:
A complex machine is a machine that is made of two or more simple machines that are working together to complete a
specific task.
The mechanical advantage of a machine is how many times easier the machine makes the work.
The goal of a machine is to maximize the mechanical advantage.
The mechanical advantage of a machine can be calculated by:
Input force/Output force.
If the mechanical advantage of a machine is greater than one, the machine is considered efficient.
You do not need to know the formulas, but you need to calculate the advantage.
All Machines
Levers
Inclined Planes
Pulleys
Wheels & Axles
Output force/
Input arm/
Length/ Height
Number of
Wheel radius/
Input force
output arm
support ropes
Axle radius
1. Input arm of a lever is 20m and the output arm is 5m. MA= _____
2. The inclined plane is 25 cm high and 150cm long. MA= _______
3. The pully pulling up a bucket is pulled over three puleys. MA= ____
4. The wheelbarrow has an axle radius of 15m and a whell raius of 16 cm. MA= ___