Ap Phys B Review - Kinematics And Newton's Laws

AP Phys B Test Review Kinematics and Newton’s Laws 4/28/2008

Overview  

Units and Dimensions Scalars and Vectors – 1-D, 2-D, and 3-D

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Particle Kinematics Newton’s Laws of Motion – Gravity – Friction

Units and Dimensions   

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Metric System Conversions Dimensional Analysis Order of Magnitude Estimations

Scalars and Vectors 

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Scalars: Magnitude only. Vectors: Magnitude and direction. – Vectors components  

Cartesian coordinates Trigonometry

– Find the magnitude of a vector

v vy θ

vx

Scalars and Vectors 

Vector Addition and Subtraction – Graphical Representation “Head to tail” – Mathematical operation

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Vector multiplication – Dot Product – Cross Product

Particle Kinematics 

Distance and Displacement – Distance: length – Displacement: length and direction

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Speed and Velocity – –

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Speed: distance/time Velocity: displacement/time

Acceleration – Change in speed (velocity)/time

Particle Kinematics 

Graphs – Distance vs. time graphs; slope – Velocity vs. time graphs; slope, area

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Instantaneous vs. average values

Particle Kinematics 

Problem Solving Strategies – Identify known quantities – Key words: at rest, constant speed

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Free fall problems – Acceleration due to gravity: 9.8 m/s2

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Use common sense!

Particle Kinematics 

Equations of Motion

v f = vi + at 1 2 d = vi t + at 2

v = v + 2ad 2 f

2 i

x Vf Vi a t d

y

Newton’s Laws 

1st law (Law of Inertia): An object at rest stays at rest, and object in motion stays in motion in a straight line at a constant speed until acted on by an outside force. – Inertia: Resistance of an object to change – Meaning: Things don’t speed up or slow down without a reason.

Newton’s Laws 

2nd Law: The acceleration of an object is proportional to the force on that object and is inversely proportional to the mass of the object. – Meaning: The heavier something is, the more force it takes to achieve a certain acceleration.

  ∑F a= m

Newton’s Laws 

3rd law: For every action, there is an equal and opposite reaction – All forces occur in pairs. – These forces cannot occur on the same object.

Newton’s Laws  

Balanced vs. Unbalanced forces; Equilibrium Free-Body Diagrams – – – – –

Determining acceleration Normal Force Tension (pulleys) Friction (static and kinetic) Inclined Plane Problems

Newton’s Laws 

Circular Force – Radial vs. tangential acceleration – Centripetal force: an unbalanced force

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Newton’s Law of Universal Gravitation – Gives the gravitational force between two objects.

2

v ac = r

GM 1M 2 Fg = 2 r