8 - Force and motion review

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Review of the vocabulary, formulae, and concepts for the 8th grade Physics unit (Force, Motion, and Energy)

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Force and motion review:

Force and motion review Vocabulary and Formulae Created by Beverley Sutton Pistor Middle School

The three important understandings:

The three important understandings Everything in the universe is in motion. Force is a push or pull that can result in a change in motion. There are laws that explain the motion of an object.

acceleration:

acceleration the rate at which velocity changes (this means increases, decreases, or changes direction). Measured in meters per second per second and written as m/s 2

acceleration

deceleration:

deceleration negative acceleration; the rate at which velocity decreases

centripetal force:

centripetal force a force that causes an object to move in a circle.

energy:

energy the ability of a physical system to do work.

force:

force a push or a pull exerted on an object.

force:

force Force = Mass X Acceleration Remember: force is measured in Newtons, mass in kilograms, and acceleration in m/s 2 Force (N) = Mass (kg) × Acceleration (m/s 2 )

friction:

friction -the force that one surface exerts on another when the two rub against each other.

gravity:

gravity the force that pulls all objects in the universe towards each other.

inertia:

inertia the tendency of an object at rest to stay at rest; and the tendency of an object in motion to stay in motion (in a straight line). Inertia is resistance to change

mass:

mass a measure of the inertia of an object; the amount of matter in an object

matter:

matter any substance which has mass and occupies space.

momentum:

momentum impetus; a vector; the property of a moving body given by its mass times its velocity (measured in kg.m /s ). AKA “Bashing” power

momentum:

momentum Momentum = Mass X Velocity Remember mass is measured in kilograms and velocity in m/s, so momentum is measured in kg.m /s Conservation of Momentum BEFORE AFTER Kg m/s Momentum Kg m/s Momentum 1000 * 0.0 0 1000 * 13.5 13500 900 * 20.0 18000 900 * 5.0 4500 TOTAL 18000 TOTAL 18000

motion:

motion the state in which one object's distance from another (the reference point) is changing.

net force:

net force the overall force on an object when all the individual forces are added together.

Newton:

Newton the unit measure of force

object:

object a tangible and visible entity (something you can touch and see).

reference point:

reference point a place or object used for comparison to determine if an object is in motion

speed:

speed Distance travelled per unit time (speed = distance/time); the rate of change in the position of an object. Measured in meters per second (m/s).

speed:

speed Remember that velocity is calculated the same way, but velocity always includes a direction.

velocity:

velocity the rate and direction of the change in the position of an object.

Variable:

Variable something measurable that changes Independent variable – variable we control Dependent variable – variable that changes as a DIRECT RESULT of what we do to the independent variable

Terminal Velocity:

Terminal Velocity Since the net force on you is zero, your acceleration will also be zero (Newton's 1 st Law). Now, you are no longer speeding up - you are moving at a constant velocity. This is called your terminal velocity . Unless something happens, this is the velocity that you will have until you hit the ground.

weight:

weight the force that gravity exerts upon a body.

Newton’s first law of motion:

Newton’s first law of motion An object at rest will remain at rest and an object in motion will remain in motion in a straight line, at a constant velocity, unless acted upon by an unbalanced force [AKA the Law of Inertia]

Newton’s second law of motion:

Newton’s second law of motion The net force on an object is equal to the product of its acceleration and mass. Force = Mass X Acceleration Acceleration = Mass =

Newton’s third law of motion:

Newton’s third law of motion For every action, there is an equal and opposite reaction.

So … remember … :

So … remember … Everything in the universe is in motion. Force is a push or pull that can result in a change in motion. There are laws that explain the motion of an object. 