[Science 1] Work Flashcards
What is work?
Using force to move an object/Transfer of energy
What is work proportional to?
Force and distance
If there is no ____, there is no work. Fill in the blank.
Force and movement
What is the difference between the forces from the two formulas, only vertical and only horizontal?
-Vertical: Force is gravity
-Horizontal: Force is the force applied in direction of the movement
What is negative work?
Force acting on opposite direction to movement (ex. air resistance, friction)
How to calculate Sin0
Opposite/Hypotenuse (SOH)
How to calculate Cos0
Adjacent/Hypotenuse (CAH)
What does the equation, Fx = F d x Cos(0) describe?
Components of an applied force acting in the direction of the motion
What does the equation, Fii (parallel) =mgSin(0) describe?
The parallel component of the gravitational force acting on an object on an incline.
Does lifting a heavy object with a small force equal less work?
No
What is power? How do you determine power?
-Work done in a certain time
-Depends on how fast you lift an object
Is power proportional or inversely proportional to time?
Inversely proportional
Is power proportional or inversely proportional to work?
Proportional
What is mechanical advantage?
Measures how much a machine helps you do work
Why does “The amount of work done at angle < the amount of work done horizontally” occur?
As 0 (theta) increases towards 90 degrees, it reduces friction
How is a moveable pulley different from a fixed pulley? What is its advantage?
Change direction and magnitude —> Gives us mechanical advantage
What is potential energy?
Energy stored in an object
What is gravitational potential energy?
Stored energy an object has due to its height above the ground (more higher—> more heavier—>more gravitational energy)
What is potential energy is proportional to?
Mass and height
What is kinetic energy is proportional to?
Mass and velocity squared
What is kinetic energy?
The energy an object has because of its motion—>faster—>more energy
Why is kinetic energy important?
Calculate braking distance (more energy —> more time taken to stop)
What is mechanical energy?
Kinetic + Potential
What are the examples of kinetic energy (movement)?
Thermal, Mechanical, Electromagnetic, Kinetic energies
What are the examples of potential energy (stored)?
Chemical, Elastic, Nuclear, Gravitational
What is an energy that is neither in the group of potential nor kinetic energies?
Sonic
What is the difference between light and radiant energies?
-Light: Specific type of radiant energy: often used in biological or vision
-Radiant: Include all types of electromagnetic radiation, both visible and invisible
What is Thermodynamics?
Study of energy
How does the Principle of Conservation differ from the Principle of Work and the Law of Thermodynamics?
-Principle of Conservation: Generalized idea that the total energy is constant and energy can only be changed from one to another, not created nor destroyed
— the others are more detailed explanations for this idea:
-Principle of Work: No matter what tool you use (ex. pulley), the amount of work you do is the same
-The First Law of Thermodynamics: In a closed system (masses are not allowed to escape and are trapped inside like a container), energy can neither be created nor destroyed, only converted from one form to another
What is the Second Law of Thermodynamics?
The entropy (measure of disorder: unavailable to do work) of any isolated system will increase. For example, if you leave a room without cleaning it for a prolonged amount of time, dust would form. You need energy to keep the room in order.
What is the Third Law of Thermodynamics?
As temperature gets closer to absolute zero (-273.15°C), the movement of particles (like atoms) slows down to almost nothing. At absolute zero, everything stops moving and entropy (disorder) reaches a constant low value (but is actually quite impossible to reach)
What does efficiency measure?
Not all energy can be used to do work. Some energy is “lost” as heat or becomes unusable. Efficiency measures how well something uses the energy supplied to it. No system is 100% efficient.
