Physics Reviewer 2nd Quarter Grade 9 PDF

PHYSICS REVIEWER 2ND QUARTER, GRADE 9 WEEK 1 : FREE FALL FREE FALL an object that falls solely due to gravity ★ Mass & rate of fall : in absence of air resistance, all objects regardless of the mass have the same rate of fall ★ Acceleration due to gravity is alway...

PHYSICS REVIEWER 2ND QUARTER, GRADE 9 WEEK 1 : FREE FALL FREE FALL an object that falls solely due to gravity ★ Mass & rate of fall : in absence of air resistance, all objects regardless of the mass have the same rate of fall ★ Acceleration due to gravity is always constant. ○ Constant acceleration : -9.8 m/s² ➔ Objects moving up = decreases by 9.8 m/s ➔ Objects moving down = increases by 9.8 m/s (with a negative symbol) ★ Velocity : for an object that is dropped, the direction of velocity is downward. It has the same direction as acceleration. ➔ At maximum height, Vy₁ = zero ➔ Free falling objects use only the Y component. ➔ In graphing, time is always the independent variable, and it is always positive. ★ Air resistance or drag is the same as air friction. ★ Examples of free falling objects ➔ A basketball thrown upward ★ A vacuum is a space with no air (resistance). An object dropped in a vacuum will have no other force than gravity acting upon it. SIGN CONVENTIONS ★ Distance above the origin are positive, while the distances below are negative ★ Upward velocities are positive; downward velocities are negative ★ Acceleration due to gravity (g) is always negative. The origin is the point of release 1 KEY FORMULAS TRANSLATIONS: DISPLACEMENT d= (½)gt² y = position POSITION y(t) = y₁ + Vy₁(t) + Vy₁ = initial velocity in the y (½)gt² component VELOCITY v = gt g = acceleration due to gravity (ALWAYS -9.8m/s²) WEEK 2 : PROJECTILE MOTION PROJECTILE MOTION ★ A concept that explains the nature of an object thrown into the air as it moves in an arc. ★ It states that the object is influenced by gravity and initial velocity, thus combining a horizontal (applied), and vertical (gravity) force. ★ Like free fall, it also neglects air resistance. ★ Consists of horizontal and vertical motions that are independent HORIZONTAL MOTION (Vx) ★ Uniform motion : horizontal velocity is constant (0m/s) ★ Does not affect the vertical motion ★ Can be determined using Vcosø where ø is the angle VERTICAL MOTION (Vy) ★ Uniformly accelerated motion : vertical velocity is changing ★ As the object moves up, the vertical velocity decreases by 9.8 m/s every second and velocity is always equal to zero at maximum height. ★ Can be determined by Vy = Vsinø ★ considered as Free fall ★ Vy = Vy ➔ Upward motion = minus 9.8, positive sign ➔ Downward motion = add 9.8, negative sign Supplementary angles = 180 Complementary angles = 90, refer to angles with the same range 2 TRAJECTORY ★ Path of a projectile which follows a parabola (U-shaped curve) ➔ Results from the combined motions in the horizontal & vertical directions ➔ Parabola ; a set of points in a plane that are equidistant from a given directrix ★ Peak of the trajectory = highest point (the vertical velocity is 0) ★ It is important to keep note that gravity is constantly pulling the object downward, therefore, acceleration due to gravity is always present. GRAPH: There is no downward velocity at the maximum height. Velocity with initial velocity (formula): ★ v = Vy1 - gt Resultant Velocity (formula): ★ V2 = √(Vx)² + (Vy)² ★ Range increases until it reaches 45°, but start to decrease beyond 45° Angle ↓ (Vy) ↑ range Angle ↑ (Vy) ↑ max height Angle ↑ (Vy) ↑ time of flight Initial Velocity ↑ (Vx) ↑ range Initial Velocity ↑ (Vx) ↑ max height Initial Velocity ↑ (Vx) ↑ time of flight 3  WEEK 3: IMPULSE, MOMENTUM AND CONSERVATION OF LINEAR MOTION MOMENTUM ★ Can be defined as mass in motion ★ Vector quantity with a direction the same as the velocity. [ SI unit = kg · m/s ] ➔ Every moving object has momentum, it may be large or small ➔ Affected by an object’s mass and velocity ★ ↑ mass = ↑ momentum = ↑ velocity ➔ At rest = no momentum ➔ At rest = ↑ inertia = ↑ mass ★ the greater the mass, the greater force needed to stop the object. ★Velocity change = momentum change The longer the net force is applied, the greater the change in momentum when solving for momentum, always ensure that the unit of mass is in kg, and the unit of velocity is m/s. IMPULSE ★ changes the momentum of an object [ n-s or kg-m/s ] ★ is equal to the change in momentum ★i=Ft CONSERVATION OF LINEAR MOMENTUM ★ Momentum is conserved when the same amount of kinetic energy and total momentum is used before and after collision. ★ Linear/Total momentum ; product of the mass of the object and its velocity. ★ Isaac Newton deduced his third law of motion (for every action, there is an equal but opposite reaction) 4  FORMULAS MOMENTUM p = mv TOTAL MOMENTUM ptotal = pi₁ + pi₂ CHANGE IN MOMENTUM i = mass x change in velocity IMPULSE i = F(t) Fnet(t) = m(Vƒ - V₁) KINETIC ENERGY VELOCITY v = p/m NET FORCE Fnet = ma Fnet = [Vƒ - V₁] / t COLLISION ★ when two or more bodies come in contact with each other resulting linear momentum TYPES OF COLLISION ★ Elastic : bodies separate after collision. Both KE and momentum are conserved. ★ Inelastic : bodies stick together, but may separate after collision. Mass is conserved, KE is not. ➔ Partial Inelastic Collision: bodies cling to each other, but also separate after collision. Some KE is lost, but momentum is still conserved. ➔ Perfectly Inelastic : bodies cling to each other after collision. KE and momentum are not conserved ★ Kinetic Energy: energy of motion ★ Potential Energy: stored energy 5  WEEK 4 : LAW OF CONSERVATION OF ENERGY ENERGY ★ refers to the capability to do work ★ cannot be created nor destroyed ★ forms of energy : heat, electrical, chemical, nuclear TWO KINDS OF ENERGY: KINETIC ENERGY ★ energy of motion or momentum ★ increases as speed increases and as it goes down POTENTIAL ENERGY ★ stored energy due to its position ★ increases as objects move up MECHANICAL ENERGY ★ energy used to do work ★ sum/total of potential & kinetic energy ★ always remains constant LIST OF FORMULAS Height Potential Energy m・g・h Speed Kinetic energy Mechanical energy TE = ½ mv² + mgh 6  WEEK 5 : ELECTRICITY ELECTRICAL QUANTITIES VOLTAGE ★ Electric potential difference between two points. (Electrical Pressure) ★ Pushes electric charges to move through a circuit. ★ [Unit: VOLTS] [ Formula: V = I x R] LIST OF FORMULAS CURRENT ★ Continuous flow of electric charges. Voltage V = I(R) ★ [Unit: amperes] [Formula: I = V/R] Current I = V/R ★ 1 ampere = 6.24 x 10¹⁸ electrons moving in one second RESISTANCE Resistance R = V/I ★ The opposition of the electrical flow. ★ Resistors: reduce the amount of current passing through a conductor. ★ ↑ Resistance = ↑ voltage needed to maintain a bulb Direct Relationship: Voltage with both Current & Resistance Inverse Relationship: Current with Resistance (vice versa) Conductor material that allows the flow of charge (electric current) in one or more directions. The cathode (-) is full of electrons that repel each other. This creates pressure, and the voltage pushes them to the anode (+) with less electron pressure. 7 ELECTRON PRESSURE ★ The negative terminal (anode)’s electron decreases while the positive terminal (cathode)’s increases. (due to the transferring of the electrons bcz of high pressure) ★ Eventually, the number of electrons on both terminals will become equal. This will cause the current to stop, and the battery to die. ★ Resistors help limit the amount of electron transferring from - → + ELECTRICAL CIRCUIT ★ A closed loop where the current flows around. ➔ Conventional current flow: positive to negative (OLD MISCONCEPTION) ➔ Electron flow: negative to positive (CORRECT) TWO TYPES OF CIRCUIT Parallel Circuit ★ components are connected to multiple paths. ★ current can flow through multiple paths, so if one component fails, others can still function. The diagram has three paths. Path 1, Path 2, Path 3 Each branch gets the full voltage (9V) of the power source so all components work at their intended power. Series Circuit ★ components are connected to only one path, and only one route to flow through. so if one component fails, the whole circuit will stop functioning. ★ Voltage Sharing: the power source’s voltage is divided among all the components. 8  THE END :P plz tell if there is kulang or mistake thx C: lia 9