Physics - Unit #3 Conservation Laws

Review for Physics midterm

What are changes in motion caused from?

Forces

What are forces originated from?

The expenditure of energy

No energy =

no force

What must be moved in order for work to be done in any system?

Mass, meaning a force will be needed

What is energy?

Energy is ability to do work and/or generate heat

Are energy and work scalars?

Yes

What does it mean for energy and work both being scalars?

There will be no assigning of positive or negative based on direction

Mechanical Energy

energy that can do work (move things)

Kinetic Energy

energy in motion (being used). An object must be in motion to have kinetic energy

Potential energy

stored energy. There are lots of ways to store energy, three examples include Gravitational, Elastic, and chemical energy

Gravitational (potential) Energy (GPE)

This is changed by changing the height of the objects; lifting it higher increases the potenital energy while lowering the object decreases the potential energy

Elastic (potential) energy (EPE)

Energy from stretched or compressed objects like springs or elastics

Chemical (Potential) energy (CPE)

energy from chemical bonds being formed or broken (this is how we get energy from processing our food, or from burning gasoline in engines)

Non-mechanical energy

energy that CAN’T do work (move things)

Work (W) formula

Work = force (F) x distance (d)

Mechanical energy formula

Mechanical energy (ME) = Kinetic energy (KE) + Potential energy (PE)

Kinetic Energy (KE) formula

½ x mass (m) x velocity squared (v²)

Potential Energy =

Gravitational (GPE)

Potential energy/gravitational (GPE) formula

mass (m) x gravity (g) x height (h)

Potential energy, elastic (EPE)

½ x k x X² where k is the “spring constant” and X is the displacement of the spring from rest, in meters

Work energy Theorem

The change in energy of an object is always equal to the amount of work done on the obejct

Conservation of energy

Energy cannot be created nor destroyed, but rather transferred from one type to another

Mechanical energy can ONLY be conserved by the absence of what?

Friction

Examples of non-mechanical energy

heat, light, sound

Energy is always…

conserved

With friction being present, what type of energy will be created from mechanical energy?

non-mechanical energy

power definition

the rate at which energy changes with respect to time, either by transfer into or out of a system/object or by conversation from one form to another within a system

Average Power definition

The amount of energy being either transferred or converted, divided by the time it took for that transfer or conversion to occur (P_avg = ΔE/Δt)

In the metric power, what unit of power would be used?

watts

momentium definition

mass in motion

momentium symbol

P (progression of motion)

Momentium..

is a vector and therefore direction is dependent

Impulse definition

the agent responsible for changing the momentium of an object

Impulse symbol

J

impulse changes…

momentium

the amount of impulse is

equal to the change in momentum

impulse is NOT

momentium

Elastic collision definition

hit and separate, KE is conserved

Inelastic Collision definition

hit and separate/bounce off of each other, KE is lost

Perfectly inelastic collisition

hit and stick together, KE is lost

Conservation of momentum definition

the total momentum of a system that remains constant, but momentum will be shifted from one object to another (in that system)

momentium formula

mass x velocity = momentium

impulse formula

force x time = impulse

momentium and impulse formula

impulse = change in momentum (Ft = m(Δv))

Elastic collision formula

m₁v_1i + m₂v_2i = m₁v_1f + m₂v_2f

perfectly inelastic collisions formula

m₁v_1i + m₂v_2i = (m₁ + m₂)v_f