Mechanics 0.0 / 5 ? PhysicsMomentum and ImpulseMotionWork, Energy, PowerASAQA Created by: goliver3Created on: 11-01-17 08:42 Vectors A scalar quanitity only has magnitude, whereas a vector quantity has both magnitude and direction Pythagoras' theorem and trigonometry is used to find resultant forces An object is in equilibrium if The resultant force acting on the object is zero The sum of clockwise and anticlockwise moments equals zero The forces create a closed triangle 1 of 7 Moments The moment of a force about a turning point is the force (N) multipled by the perpendicular distance from force to turning point (m) Moments are measured in newton metres (Nm) Sum of clockwise moments = sum of anticlockwise moments when in equilibrium A couple is two equal forces acting in opposite directions but not through the same point, creating a turning effect The moment of a couple is calculated by multiplying the size of one of the forces by the perpendicular distance between the two forces The centre of mass of an object is the point at which all mass appears to act In a uniform object the centre of mass is in the centre of the object 2 of 7 Motion Along A Straight Line S = displacement (m) U = initial velocity (ms^-1) V = final velocity (ms^-1) A = acceleration (ms^-2) T = time (s) V = change in s/change in t A = change in v/change in t 3 of 7 Newton's Laws Of Motion Newton's first law An object continues in a state of rest or uniform motion in a straight line unless acted on by a resultant force Newton's second law The rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force F = force (N) M = mass (kg) A = acceleration (ms^-2) change in(mv) = change in momentum (kg ms^-1) F = ma F = change in(mv)/change in t Newton's third law When two objects interact they exert equal and opposite forces on each other 4 of 7 Work, Energy, & Power W = work done (J) F = force (N) S = displacement (m) Theta = angle between the direction of motion of the object and the direction of the force (degrees), P = power (W) V = velocity (ms^-1) W = Fs*cos theta P = change in W/change in t P = Fv 5 of 7 Conversation Of Energy Change in Ep = change in gravitational potential energy (J), Ek = kinetic energy in joules (J) Change in Ep = mg*change in h Ek = 1/2mv^2 6 of 7 Momentum Concepts Newton's second law The resultant force is equal to the rate of change of momentum p (momentum) = mv Impulse (kgms^-1) = F change in t F*change in t = change in(mv) 7 of 7
Comments
No comments have yet been made