8 - Force and motion review

Category: Education

Presentation Description

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


Presentation Transcript

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 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




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 the ability of a physical system to do work.


force a push or a pull exerted on an object.


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


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


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


matter any substance which has mass and occupies space.


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 = 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 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 the unit measure of force


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


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


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 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.

authorStream Live Help