physics

unit 3 and 4

what is a vector?

quantity that has magnitude and direction; represented with arrow or tilda (~)

what is the resultant vector?

result of two or more vectors combined, either through vector addition or subtraction

how to resolve vectors into components?

1. resolve each vector into their horizontal and vertical components (v1 x and y, and v2 x and y)

2. if two vectors are in different directions, put head to tail and find the net vector of horizontal and vertical directions (vx = v1x + v2x; vy = v1y + v2y)

3. find magnitude and direction using tan

4. bearing or compass in correct quadrats with direction

what are the horizontal and vertical components of velocity?

independent components of each other; resolution of a projectile’s velocity in the horizontal or vertical direction

what is initial velocity’s components?

ux = u cos θ, uy = u sin θ

what happens at maximum height?

vy = 0

what is final impact in projectile motion?

vx and vy (convert final velocity components into magnitude and direction)

what are complementary angles?

those that add up to 90 degrees e.g 60 and 30; projectile released at ground level will achieve maximum range at 45 degrees

what is applied force (Fa)?

force applied to an object by a person or another object on a flat surface; Fv = FA sin θ, Fh = Fa cos θ

what is weight?

force of gravity acting on an object; Fg = mg

how to get parallel (to surface) force?

Fp = Fg sin θ

how to get perpendicular (to surface) force?

Fperpendicular = Fg cos θ

what is the normal force for an object at rest on horizontal surface with no other forces acting?

Fn = -Fg

what is the tension force for a hanging object at rest?

Ft = Fg

what is the net force for an object moving on flat surface in horizontal direction?

Fnet = Fh (Fa cos θ) + Ff

what is the net force for a hanging object moving in vertical direction?

Fnet = Ft + Fg

what is the normal force for an object being pulled on flat surface?

Fn = Fg - Fv

what is the normal force for an object being pushed on flat surface?

Fn = Fg + Fv

what is the frictional force for an object on flat surface?

rearrange Fnet = Fh + Ff

what happens when an object is at rest or travelling at constant speed on flat surface?

Ff = Fh (same in magnitude but opposite direction)

what is the net force for an object sliding down incline with no friction?

Fnet = Fp

what is the net force for an object sliding down incline with friction?

Fnet = Fp - Ff

what is the net force for an object pulled up incline with no friction?

Fnet = Ft - Fp (but if constant speed, Fnet = 0 therefore Ft = Fp)

what is the down the incline force for an object pulled up incline with friction using a hanging mass?

Fdown = Fp + Ff

what is the equation for hanging mass up the slope?

m2g - Fup = m2a

what is the equation for overall mass on the slope?

Fup - Fp - Ff = m1a

what is uniform circular motion?

motion of an object travelling at a constant speed in circle

what is a revolution?

circular motion of an object around another

what is a rotation?

circular motion of an object around its own axis

what is centripetal force?

force acting on an object travelling with uniform circular motion that pushes or pulls object towards centre of motion (Fc)

what is centripetal acceleration?

acceleration experienced by an object moving in a circular path towards centre of motion

what is a period in circular motion?

time taken for an object to complete one revolution around centre of motion

what is tangential velocity?

linear velocity of an object undergoing circular motion where the magnitude is the speed of the object and the direction is a tangent to circular path of motion

what is rotational speed?

number of revolutions an object does per second

what is average speed in circular motion?

The total distance traveled by an object divided by the total time taken to cover that distance

how to calculate a period in circular motion?

T = time/number of revolutions

what is gravity?

force of attraction between objects with a mass

what is newtons law of universal gravitation?

force of attraction between each pair of point particles is directly proportional to product of their masses and inversely proportional to square of distance between them → Fg = GMm/r² (m/M is masses of objects)

what is a gravitational field?

region of space surrounding a body in which another body experiences a force of gravitational attraction

what are the units for gravitational force?

radial distance = m

G = N m² kg^-22

mass = kg

what is gravitational field strength (g)?

net force (F) per unit mass (m) at a particular point in gravitational field

what are the units for gravitational field strength?

N/kg

what is keplers first law of planetary motion?

law of orbits - all planets move about the sun in elliptical orbits. having the sun as one of their foci

what is keplers second law of planetary motion?

law of areas - a radius vector joining any planet to the sun sweeps out in equal areas at equal lengths of time

what is keplers third law of planetary motion?

harmonic law/law of periods - square of sidereal period of a planet is directly proportional to the cube of its mean distance from the sun

→ T² is directly proportional to r³ (radius of orbit)

what is the formula of kepler and newtons third laws combined?

gravitational force = centripetal force, so Fg = Fc where T²/r³=4pi²/GM

what is coulomb’s law?

states that like charges repel and opposite charges attract, with a force proportional to the product of electric charges and inversely proportional to the square of the distance between them (1.6×10^-19 J)

what is coulomb’s law expressed as?

F = (coulomb constant) x Qq/r² where r is radial distance in m, Q and q is charge in coulombs

what is the appropriate notation for coulomb’s law problems?

Fab = force acting on A due to B (positive to negative)

what is an electric field?

region of space in which an electrified object will experience a force due to presence of electric charges

what is electric field strength?

intensity of an electric field at a particular location in that field; measure of force acting on a unit charge (q) placed at that point in the field

what is the formula for electric field strength?

E=f/q or E= k x q/r²

when will electric field strength be 0?

when Ea = Eb

what is electric potential energy?

capacity of electric charge carriers to do work due to their position in the field

what is a uniform electric field?

has a constant field strength and found between charged parallel plates