Pre-AP Physics – Chapter 1 Notes – Yockers – JHS …

1 Pre-AP Physics Chapter 1 Notes Yockers JHS 2008 Standards of Length, Mass, and Time ( quantities)- length - mass - time Derived Quantities: Examples Dimensional Analysis useful to check equations and to assist in deriving expressions- L = length; M = mass; and T = timeConversion of Units multiplying a quantity by a conversion factor () withnumerator and denominator having different units to provide the desired units in the final result. Importance?!Geometry / Trigonometry / AlgebraSignificant Figures measured values are known only to within the limits of experimentaluncertainty (quality of apparatus, skill of experimenter, number of measurements)- When ,the number of significant figures in the final answer is thesame as the number of significant figures in the quantity having the number ofsignificant When numbers are , the number of decimal places in the result shouldequal the smallest number of decimal places of any term in the After you are done with Chapter 1 (and for the AP Exam)

2 Significant figures is a Systems used to specify locations in space consist of- a fixed reference point O, called the - a set of specified axes or directions with - instructions that explain how to label a point in space relative to the origin and axes- the (rectangular) and/or coordinate systems will be used unlessspecifiedVectors and Scalars- scalar a quantity that is completely specified by a positive or negative number withappropriate - vector a quantity that must be specified by both since velocity, v, is a vector, it should be written as either v or velocity s magnitude (always positive) could be written as v or Pre-AP Physics Chapter 2 Notes Yockers JHS 2008 KINEMATICS (1-Dimensional Motion)Motion/Strobe diagramsImportance of coordinate systems and specifying direction of vectorsDisplacement (general)

3 Where d = displacement (change in position)- displacement for an object at rest = - displacement can be positive or negative- displacement does not equal (horizontal)(vertical)- displacement has both magnitude and direction (vector) vector is a physical quantity that requires the specification of both scalar is a quantity that has Velocity the quantity that measures how Average velocity total displacement divided by the time interval during which the displacementoccurred (m/s)- speed does not equal velocity has magnitude and direction, and speed only has - average velocity can equal slope if s and t are graphed steeper slope = position-time graph that is parallel to time axis (x axis) has a position that does notchange over time (velocity of m/s)

4 - slope allows you to determine vavg over short or long time intervals instantaneous velocity the limit of the average velocity as the time interval tbecomes infinitesimally short the slope of the line tangent to the position-time curve at a given point is theinstantaneous velocity at that corresponding time instantaneous speed (scalar) is defined as the magnitude of the instantaneousvelocity (speed can never be negative)- equation of motion for average velocityPre-AP Physics Chapter 3 Notes Yockers JHS 2008 KINEMATICS (1-Dimensional Motion)Acceleration - velocity-time graphs- motion/strobe diagramsAverage acceleration the change in velocity divided by the time interval during which the changeoccurs(m/s)/s = m/s2- acceleration is a vector quantity (direction and magnitude)

5 - acceleration can be either when an object s velocity and acceleration are in the direction, the speed of theobject with time when an object s velocity and acceleration are in directions, the speed of theobject with timeOne-dimensional motion with constant acceleration- when acceleration is constant, average acceleration equals instantaneous acceleration or- for constant acceleration (final velocity with average acceleration)- since velocity is increasing or decreasing uniformly with time (constant a), the averagevelocity in any time interval can be expressed as the arithmetic average of the initialvelocity and the final velocity- now we can determine the displacement of an object as a function of time()ffiiffiifavgiftvvdtvvdtvdd ++= ++=+=212 or, by substituting favgiftavv += remember, this is for a constant a- to relate displacement, velocity, and acceleration without time (di is usually considered to be 0)

6 Free-fall- a freely falling object is an object moving under the influence of only, regardless of itsinitial motion- objects thrown upward or downward and those released from rest are all falling freely oncethey are - once in free-fall, all objects have an acceleration , which is the free-fall accelerationg (m/s2)- all of the previous formulas can be applied to free-fall situations by replacing the generaldisplacement symbol s with the vertical displacement symbol yPre-AP Physics Chapter 4 Notes Yockers JHS 2008 Forces In One Dimension (Newton s Laws)Force represents the interaction of an object with its - forces cause - SI unit for force is the newton (N)

7 1 N equals the amount of force that, when acting on a 1 kg mass, produces anacceleration of 1 m/s2 1 N = 1 kg x 1 m/s2 F = ma- forces can act through contact forces field forces exists between objects - gravity (gravitational field)- electricity (electric field)- magnetism (magnetic field) fundamental forces that act on elementary particles are all field forces- force depends upon (force is a quantity)- diagrams that show force vectors as arrows are called - free-body diagrams are used to analyze only the forces affecting the motion of Newton s First Law- what is the motion of an object before forces are applied?

8 Will an object with no force acting on it always be at rest?- Galileo realized (1630s) that a block sliding on a perfectly smooth surface would in the absence of an an object s nature is to maintain its Newton developed this idea further- Newton s first law (the Law of Inertia) when the net external force on an object is , itsacceleration is inertia the tendency of an object net external force can be determined by a - an object s change in motion is the same as if the were theonly force acting on the object external force is a single force that acts on an object as a result of the interactionbetween the object and its environment net external force is the - mass is a measurement of in a body which has more inertia?

9 - bowling ball or a golf ball?- football: lineman or runningback? inertia is directly proportional to - mass body accelerates under an applied force- equilibrium the state of a body in which there is - Newton s first law describes equilibrium a body is in equilibrium when Newton s Second Law force is proportional to - the acceleration of an object is directly proportional to the net external force acting on theobject and inversely proportional to the mass of the object F a (constant m) m a (constant F)or if the net external force is zero, then- - - Newton s Third Law force always exists in pairs (action-reaction pair).

10 - if two bodies interact, the magnitude of the force exerted on object 1 by object 2 isequal to the magnitude of the force simultaneously exerted on object 2 by object 1, and the two forces are opposite in direction- for every action there is an action-reaction pair remember, reaction force occurs at as the action force thus, either force can be considered either the action force or the reaction force- action-reaction pairs may not result in equilibrium because they act Weight measure of the magnitude of exerted on an object- 1 lb = N- 1 N = lb- Fg (W) is the force exerted by the Earth on an object ( ) because weight is dependent on gravity, weight depends on remember, does not change weight is not an inherent property of an object objects weigh less at higher altitudes because ag decreases with increasing distancefrom the center of the EarthNormal Force (FN)