16 - circular motion Flashcards
angular displacement
the angle of arc through which the object has moved from its starting position, theta, always in radians
radian
the angle subtended at the centre of a circle by an arc of length equal to the radius of a circle
angular displacement =
length of arc / radius
degrees to radians
times by pi/180
radians to degrees
times by 180/pi
velocity
rate of change of an object’s displacement, vector
speed
the rate of change of the distance moved by an object, scalar
angular speed
angular displacement per unit time, symbol w
angular speed =
angular displacement/ time taken
w =
2pi / T
relate speed and angular speed
v = wr
Newton’s first law
an object remains at rest or travels at constant velocity unless it is acted on by a resultant force
centripetal force
the resultant force acting on an object towards the centre of the circle when the object is rotating round that circle at constant speed
velocity round a circle is
. at right angles to centripetal force
. directed towrds the centre of the circle
what is always at right angles to a spinning object’s velocity
. centripetal force
. centripetal acceleration
centripetal acceleration
the acceleration of an object towards the center of the circle when the object is rotating at constant speed round that circle, symbol a
centripetal acceleration formula
a = v²/r
a = rw²
newton’s second law
resultant force is proportional/equal to mass*acceleration OR resultant force is proportional to rate of change of momentum of the body
centripetal force formula
F = mv²/r
F = mrw²
orbital speed (g involvement)
mg = mv² / r
g = v² / r
