Conceptual Physics (Exam 2) Flashcards
Physics
What is work?
Work= applying a force to an object over a specific distance.
What has to be present for work to be done?
- Force Applied
- Distance Traveled
- Force has to be in the same direction as motion.
Work Equation
W = F x D
Labeled in Joules
What is power?
Power: The rate at which work is done
How are power and work related?
Power and work are inversely related…as one increases the other decreases.
Power Equation
Power = Work/Time
Labeled in Watts
What is energy?
Energy: The ability to do work.
All energy types are labeled in Joules.
What are the different types of energy?
- Kinetic Energy
- Potential Energy
- Thermal Energy
- Light
- Sound
- Mechanical Energy
- Wind
- Nuclear
- Geothermal
What is Potential Energy?
Potential energy is STORED energy
1. Elastic (Rubber Band)
2. Gravitational (Positione above Earth)
3. Chemical (Chemical Reaction)
GPE
PE = mgh (mass (kg), g = acceleration due to gravity (9.8 m/s2), h = height in meters)
IF THE MASSES ARE EQUAL AND HEIGHT ARE EQUAL GPE IS EQUAL, AND THE AMOUNT OF WORK TO GET TO THE GPE IS EQUAL.
What is Kinetic Energy?
Kinetic Energy is energy in MOTION
KE = 1/2 mv 2
Labeled in Joules
IN ORDER FOR OBJECTS TO MOVE KINETIC ENERGY; NEED TO KNOW MASS AND IT HAS TO MOVE.
Law of Conservation of Energy
States that energy is neither created nor destroyed, but can be transformed from 1 form to another.
Ex: Kinetic Energy to heat; Potential energy to sound.
Work to Energy
Work = Change in Energy
What is Thermal Energy?
Thermal Energy: Amount of heat an object possesses. This is based on physical characteristics such as mass & composition.
(It is possible for an object to have more energy, but not change its temperature (Because mass has differences))
What is heat?
Heat: Flow of Thermal Energy.
Always occurs from warmer objects to colder objects.
Measure of the TOTAL kinetic energy of a system.
What is temperature?
The measure of the AVERAGE kinetic energy of a system.
How do Thermal Energy & Temperature Relate/Differ
Thermal energy and temperature have a direct relationship.
Relationship: As 1 increases, the other increases.
Differ: Temperature is the measure of AVERAGE kinetic energy while Thermal Energy is the measure of TOTAL kinetic energy of the body.
What is Specific Heat?
The amount of energy required to raise the temperature of 1 g of a substance 1 C
Specific Heat depends on MASS and The MATERIAL of the object.
Insulators: have HIGHER specific heats than conductors
How do we measure heat and temp?
- Celsius (°C)
- Kelvin (K).
- Fahrenheit (expressed as °F)
Thermometers measure temperature by using materials that expand or contract when heated or cooled.
What are Thermal Insulators?
Insulators are materials that don’t allow thermal energy to pass through easily.
What are Thermal Conductors?
Conductors are materials that allow thermal energy to pass easily through.
What simple machines are in the Lever Family?
Lever, Pulley, Wheel and Axle
What simple machines are in the Inclined Plane Family?
Inclined Plane, Wedge, Screw
What is Mechanical Advantage?
The number of times that the effort force is multiplied.
What is AMA?
Actual Mechanical Advantage (Fr/Fe)
Since the “real-world” is not perfect…this is the mechanical advantage that we “actually” get out of a machine.
Is the ratio of the output forces exerted by a machine to input force applied to it.
It represents how much the machine amplifies it increases input force
AMA is always less than IMA due to factors such as friction and other inefficiencies in the machine.
What is IMA?
IMA: Ideal Mechanical Advantage (De/Dr)
If all things were “perfect” this would be the number of times our effort force is multiplied.
IMA is the ratio of the distance over which the output force is exerted to the distance over which the input force is applied
It represents the theoretical mechanical advantage of the machine in the absence of friction and other inefficiencies.
IMA is calculated based on physical dimensions and geometry.
Why will AMA never be equal to the IMA?
Because of friction, you have to overcome friction. The least amount of friction, the more of a chance you get to ideal.
Reduce friction, and change the type of friction.
AMA takes into account the actual performance, of IMA based on ideal conditions.
Friction reduces the AMA of the machine compared to IMA.
Lever
a rigid bar resting on a pivot
Pulley
a wheel with a grooved rim around which a cord passes
Wheel and Axle
a simple machine consisting of a large disc wrapped around a smaller rod
Inclined Plane
a plane surface raised to the horizon, or forming with a horizontal plane any angle but a right angle.
Wedge
a piece of hard material with two principal faces meeting in a sharply acute angle, for raising, holding, or splitting objects.
Screw
a simple machine consisting of an incline plane wrapped around a rod.
