Kinetic Energy & Potential Energy Flashcards
(energy of motion) An object’s state of motion can be described by looking at the amount of kinetic energy that the object has at that moment in time. Since the state of motion of an object can change with time, the kinetic energy of an object can also change with time. The amount of kinetic energy that an object possesses is dependent on two factors: mass and velocity, which are directly proportional to kinetic energy. So, if the mass of an object doubles, its kinetic energy doubles as well. If it increases by 5, the kinetic energy increases by 5, and vice versa.
Kinetic Energy
The energy of an object due to its motion and position. Mechanical energy is usually used to describe a large object. It is the sum of kinetic and potential energy which can be broken down into two forms: Gravitational and Elastic, depending upon how the energy is stored.
Mechanical Energy
The energy of an object that is not due to its motion or position. Non-mechanical energy describes an object at its atomic level. Some examples of energy include electrical, chemical, thermal, and sound.
Non-Mechanical Energy
The heavier the object is, the more GPE the object has.
Mass
The speed of an object with direction.
Velocity
KE = ½mvˆ2
Kinetic Energy Equation
(stored energy) The energy stored in an object due to the object’s position.
Potential Energy
This energy is due to elevated positions. It is stored energy and it can be used at a later time to cause an object to move. For example, once a person steps off a diving board, the gravitational potential energy is converted into kinetic energy and the person falls (moves).
Gravitational Potential Energy
The larger the ‘g’, the more GPE the object has. Since gravity on Earth is considered a constant, this will not change (9.8m/sˆ2).
Gravitational Acceleration
The higher the object is off the ground, the more GPE the object has.
Height
GPE = mgh
Gravitational Potential Energy Equation
This energy is determined by two factors: the elasticity of the material and how far it is stretched or compressed. The larger the distance the elastic material is stretched or compressed the more elastic potential energy it has.
Elastic Potential Energy
The more elastic a material is, the more elastic potential energy it has.
Elasticity
When an object is neither stretched nor compressed and has no potential energy.
Relaxed State
When an object is stretched or pulled, increasing its length compared to its relaxed length.
Strethcing
When an object is squeezed.
Compressing
If an object moves in the same direction as the direction of the force applied to it, the energy of the system is increased. | W > 0 | People pushing a truck can get it to move.
Positive Work
If an object moves in a direction opposite to the direction of the force applied to it. | W < 0 | For example, parachutes move downwards, while air resistance acts upwards on the parachute.
Negative Work
If an object does not move even when there is a force applied to it, then there is no work done on the object. | W = 0 J | People exerting a force on a wall but the wall not moving would be an example of zero work.
Zero Work
