# SS 2 Physics (1st Term) ## MACHINES

Machines make our work simpler. It is a force producing device by which a large force called load can be overcome by a small applied force called effort Terminologies Used In Machines FORCE RATIO (MECHANICAL ADVANTAGE ) VELOCITY RATIO EFFICIENCY MECHANICAL ADVANTAGE We define effort as the force applied to a machine and load as the resistance overcome by the machine. The ability of a machine to overcome a large load through a small effort is known as its mechanical advantage .It is given by M.A = Load/ Effort The mechanical advantage of a machine is influenced by friction in parts VELOCITY RATIO (V.R) The velocity ratio is the ratio of distance moved by the effort and load in the same interval V.R = Distance moved by effort Distance moved by the load The velocity ratio depends on the geometry of the machine EFFICIENCY (E) The efficiency of a machine… Read More »MACHINES ## SIMPLE HARMONIC MOTION

This is the periodic motion  of  a body or particle  along a straight  line  such that the acceleration of  the body  is directed  towards  a fixed  point . A particle undergoing simple harmonic motion will move to and fro in a straight line under the influence of a force. This influential force is called a restoring force as it always directs the particle back to its equilibrium position. Examples of simple harmonic motions are loaded test tube in a liquid iiMass  on a string iii   The simple pendulum As the particle P moves round the circle once, it sweeps through an angle θ = 360 (or 2π radians) in the time T the period of motion. The rate of change of the angle θ with time (t) is known as the angular velocity ω Angular velocity (ω)   is defined by ω = angle turned  through  by the body Time taken… Read More »SIMPLE HARMONIC MOTION ## EQUILIBRIUM OF FORCES

CONDITIONS FOR EQUILIBRIUM   A body is said to be in equilibrium if under the action of several forces, it does accelerate or rotate. The sum of the upward forces must be equal to the sum of the downward forces. The sum of the clockwise moment above a point must be equal to the sum of anticlockwise moment about the same point   F1 + F2 = F3 + F4 (F1+F2) – (F3+F4) = 0 Clockwise moment = F2X2 + F4X4 Anticlockwise moment = F1X1+ F3X3 (F1X1+ F3X3) – (F2X2 + F4X4) = 0 Sum of clockwise moment = sum of anticlockwise moment MOMENT OF A FORCE The moment of a force is the product of the force and the perpendicular distance M = F x distance Unit =Nm   COUPLE A couple is a system of two parallel, equal and opposite forces acting along the same line The moment… Read More »EQUILIBRIUM OF FORCES ## NEWTON’S LAW OF MOTION

NEWTON’S LAWS OF MOTION Newton’s first law of motion states that everybody continues in its state of rest or of uniform motion in straight line unless it is acted upon by a force. The tendency of a body to remain at rest or, if moving, to continue its motion in a straight line is called the inertia. That is why Newton’s first law is otherwise referred to as the law of inertia.  Newton’s second law of motion states that the rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in of the force. F α mv –mu t F α m (v –u) t F α ma F = kma Where k =1 F =ma MOMENTUM Momentum of a body is the product of the mass and velocity of the body. The S.I. unit of momentum is kgm/s.… Read More »NEWTON’S LAW OF MOTION ## PROJECTILES AND ITS APPLICATION

MEANING OF PROJECTILE A projectile motion is one that follows a curved or parabolic path .It is due to two independent motions at right angle to each other .These motions are a horizontal constant velocity a vertical free fall due  to gravity Examples of projectile motion are the motion of; a thrown rubber ball re-bouncing from a wall An athlete doing the high jump A stone released from a catapult A bullet fired from a gum A cricket ball thrown against a vertical wall. U y                                    Hmax t                                     t     )θ P                                    Ux                                         Q Uy = U sin θ                   (vertical component)      ——————- 1 Ux = U cos θ         (horizontal component) ——————- 2 TERMS ASSOCIATED WITH PROJECTILE Time of flight (T) – The time of flight of a projectile is the time required for it to return to the same level from which it projected. t= time to… Read More »PROJECTILES AND ITS APPLICATION ## DERIVATION OF EQUATONS OF LINEAR MOTION

BASIC DEFINITIONS Displacement: This is the distance traveled in a specified direction. It is a vector quantity. Its unit is metres Distance: This is the space or separation between two points. It is a scalar quantity. Its unit is metres Speed: this is the rate of change of distance with time. It is a scalar quantity. Its unit is metre per seconds (m/s) Speed= distance Time Velocity: this is the rate of change of distance with displacement with time. It is a vector quantity. Its unit is metre per seconds (m/s) Velocity= displacement Time Acceleration: this is the increasing rate of change of distance with time. It is a vector quantity. Its unit is metre per seconds-square (m/s2). Retardation or deceleration is a negative acceleration. Acceleration= velocity Time EVALUATION I Sketch the velocity-time graph for a body that starts from rest and accelerates uniformly to a certain velocity. If it… Read More »DERIVATION OF EQUATONS OF LINEAR MOTION ## SCALAR AND VECTOR QUANTITIES

CONCEPT OF SCALAR AND VECTOR QUANTITIES Physical quantities are divided into scalar and vector quantities. A scalar is one which has only magnitude (size) e.g. distance, speed, temperature, volume, work, energy, power, mass etc. A vector quantity has both magnitude and direction e.g. force, weight, magnetic flux, electric fields, gravitational   fields etc. VECTOR REPRESENTATION A vector quantity can be graphically represented by a line drawn so that the length of the line denotes the magnitude of the quantity. The direction of the vector is shown by the arrow head. ADDITION AND SUBTRACTION OF VECTORS Two or more vectors acting on a body in a specified direction can be combined to produce a single vector having the same effect. The single vector is called the resultant. For example: (a)  Two forces Y and X with magnitude of 3N and 4N respectively acting along the same direction will produce a resultant of… Read More »SCALAR AND VECTOR QUANTITIES ## POSITION, DISTANCE AND DISPLACEMENT

POSITION The position of an object in space or on a plane is the point at which the object can be located with reference to a given point (the origin). DISTANCE This is a measure of the separation between two points. It has magnitude but no direction. Hence, it is a scalar quantity   DETERMINATION OF DISTANCE BETWEEN TWO POINTS If two points A and B located in a plane are defined by two ordered pair of values(X1 Y1) and (X2 Y2) or assumed to be in space where they are defined by (X1, Y1, Z1) and (X2, Y2, Z2) the distance between them can be determined by applying this relation. OR DISPLACEMENT Displacement is the distance covered in a specified direction. It is a vector quantity, which has the same unit as distance. ONLINE WORK What is displacement and why is it regarded as vector quantity? Highlight three differences… Read More »POSITION, DISTANCE AND DISPLACEMENT

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