advertisement

Midyear Review Regents Physics (Not on the Reference Tables) Fundamental units Mechanics Mass (m): = inertia, amount of matter, constant from place to place, units: kg Quantity Units Symbol Length meter m Mass kilogram kg Time second s Weight (Fg): = force of gravity, changes from place to place, units: N Formula: Fg = mg Equilibrium: no net force, no acceleration, constant velocity or at rest, forces form a closed figure. Concurrent vectors: are added tip to tail. Component vectors: any vector has both X and Y components. Add components to get resultant. V2 = Vx2 + Vy2 Angle : = tan-1[Y/x] Resultant force = Fnet : head-to-head and tail-to-tail with components Derived units Quantity symbol Velocity m/s acceleration m/s2 N/kg force Momentum N Kg m/s kg m/s Ns Work, Heat Energy J Nm Voltage V J/C Frequency Hz 1/sec Period sec & Impulse also Kg m2/s2 Newton’s Law of Universal Gravitation Equilibrant: Gm1m2 Fg r2 equal and opposite to resultant Two names for little “g”: 1) acceleration due to gravity, units: m/s2, formula: g = GM/r2 2) gravitational field strength, units: N/kg, formula: g = Fg/m Vectors Scalars (magnitude only) Distance Speed Mass speed Anything else! Vectors (magnitude and direction) – only 9! Displacement Velocity Acceleration Force (weight, normal force, etc.) Momentum Impulse Fields (gravitational, electric, magnetic) Resultant Concurrent Equilibrant Maximum 2 Θ = 00 Minimum 2 Θ = 1800 5 5 7 3 Triangle rule sum of any 2 sides ≥ third side for forces to be in equilibrium Inclined Plane Newton’s Third Law: Whenever A exerts force on B, B exerts equal/opposite force on A. (Action/reaction pairs: bat and ball, Earth and Moon, hammer and nail) FA FF FT FN F║ = m g sinθ Forces are the same but the effects of the forces are not: FG mA = Ma F┴ = m g cosθ Circular Motion Friction Static friction (at rest) = applied force until motion starts Kinetic friction (in motion) is constant Maximum static friction is greater than kinetic friction d Constant Velocity Graphs of Motion v t Slope = velocity t Slope = acceleration Area = displacement Two Types of Motion Constant Acceleration Forces are balanced Fnet = 0, a = 0 In equilibrium Newton’s first law Forces are unbalanced Fnet ≠ 0, a ≠ 0 not in equilibrium Newton’s second law Distance v. time Distance v. Speed v. time time Speed v. time Acceleration v. time Acceleration v. time Projectiles Horizontal Launch x Y d h t The same a 0 9.81 vi vi 0 vf vi vavg vi Angle Launch x dx = Vxt Y Whole half 0 Vx 9.81 Vy vf Vx 0 (top) vavg Vx Horizontal – constant speed Vertical – constant acceleration d t a vi T1/2 = Viy/9.8 Max range 45o max time 90o V2 = Vx2 + Vy2 Angle : = tan-1[Y/x]