Chapter 5.1 The Nature of Energy Flashcards
ENERGY
- Is the capacity to do WORK or
2. The capacity to transfer HEAT
WORK
.is the energy used to cause an object to move against force over some distance.
. (w)
. the energy transferred when a force moves an object
. w= f x d ( force ( e.g gravity ) x the distance the object move)
HEAT
Is the energy used to cause the temperature of an object to increase.
. It is the energy transferred from a hotter object to a colder one
2 Ways that and object can possess energy
- Kinetic
2. Potential
KINETIC ENERGY
the energy of motion
Is the energy an object possesses by virtue of its motion
Ek
is the magnitude of kinetic energy Ek=1/2mv2
The magnitude of kinetic energy of an object depends on
its mass (m) and speed (v)
the magnitude of kinetic energy formula Ek=
Ek =1/2mv^2
what happens to kinetic energy of an object as speed and mass increases
Kinetic energy increases. The faster the the object the larger the kinetic energy.
The lager the object the larger the kinetic energy
POTENTIAL ENERGY
.An object has potential energy by virtue of its position relative to other objects
.the stored energy that arises from the attractions and repulsions an object experiences in relation to other objects.
Instead of forces such as gravity that give rise to potential energy in relation to other objects. What is the force that attracts and repulses atoms and molecules?
Electrical charges
The most important form of potential energy when dealing with atoms and molecules
ELECTROSTATIC POTENTIAL ENERGY
ELECTROSTATIC POTENTIAL ENERGY
- E(eb)
- Arises from the interactions between 2 charged particles.
- This energy is proportional to
1. the ELECTRICAL CHARGES on 2 interacting atoms, Q1, and Q2 and
2. inversely proportional to the DISTANCE, d, separating them
THE ZERO OF ELECTROSTATIC POTENTIAL ENERGY
is defined as infinite separation of the charged particles. At infinite separation the magnitude of electrostatic potential energy is zero.
LIKE CHARGES AND Eel
REPULSION
.Smaller separation = greater repulsion = higher Eel
. Greater separation = less repulsion=lower Eel
OPPOSITE CHARGES AND Eel
ATTRACTION
. Smaller separation = greater attraction=lower Eel
. Greater separation = less attraction= higher ( less negative ) Eel)
1J= ? KG
1 kg-m^2/s^2
SYSTEM
The portion of the universe that is singled out for study to track the energy changes that occur
SURROUNDINGS
All the parts of the universe that is not the system
The 3 types of system
- open
- closed
- isolated
The SI unit for energy
JOULE
1calorie(cal)
. In terms of joules
The amount of energy required to raise the temperature of 1 g of water from 14.5 C to 15.5 C
. 1 cal = 4.184 J
A nutritional Calorie
1 Cal = 1000 cal = 1 kcal
CLOSED SYSTEM
Systems that can exchange energy but not matter with their surroundings. No mass is lossed or gained from its surroundings. but energy is exchanged in the form of heat and work
ISOLATED SYSTEM
where neither energy nor matter can be exchanged with surroundings
FORCE
Any push or pull exerted on an object
mass x gravity
THERMODYNAMICS
the study of energy and its transformations
OPEN SYSTEM
is one in which matter and energy can be exchanged with the surroundings.
e.g.a pot of boiling water on a stove
THERMOCHEMISTRY
The portion of thermochemistry a portion of thermodynamics that examine the relationship between chemical reactions and energy changes that involve heat.
What happens to potential energy as it is converted into kinetic energy and speed increases
potential energy decreases ( also decreases as a force : repulsion or attraction decrease potential energy decreases)
what happens to speed when kinetic energy is converted to potential energy
speed is decreased
Heat
Is the energy transferred from a hotter object to a colder one
CHEMICAL ENERGY ( e.g. from fuels)
Many substances release chemical energy : energy due the potential energy stored in the bonds of its atoms.
A substance THERMAL ENERGY is
is the energy it posses because of its temperature is associated with the KINETIC ENERGY of the molecules in the substance.
