Phyiscs Circular Motions
Term 3
Uniform Circular Motion
When a body moves in a circular path with a constant speed, it is said to undergo uniform circular motion. Although the speed is constant, velocity is continually changing, since it is constantly changing its direction of motion.
Centripetal
V
V
ac ac Acceleration is directed towards the centre of the circle and is therefore called “centripetal acceleration.” ac =v^2r
ac =v^2r
If T is the time taken for one revolution then: V = 2πrT ac =v^2r = (2πrT)^2r = 4π^2r^2T^2r
= 4π^2rT^2
Let us work with ac against T^2 on graphs.
Note:
Frequency is the number of revolutions completed per seconds. Cycles/seconds
Centripetal Force
… is the force responsible for centripetal acceleration. Hence the centripetal force may be defined as the force directed towards the centre of the circular path responsible for restraining the object to undergo uniform circular motion.
Fc= m.v^2r
Example
A car of mass 1.20X10^3 kg is rounding a curve of radius 1.55X10^3m at a speed of 25.0m/s/
Find: 1. The centripetal acceleration. 2. the centripetal force
ac =v^2r
Non-Uniform Circular Motion Vertical Circle Resultant force toward the centre is
FNET = FC= mv2r Top: mv2r = mg + Tension Bottom: mv2r = tension - mg
Universal Law of Gravitation
Everybody in the universe attracts every other body in the universe with a force that is proportional to the product of their masses, and inversely proportional to the square of the distance between them. This force acts along the line joining the two masses.
G is called the universal gravitational constant, and its value is 6.67 X 10-11
Eg.
What happens to the forces of attraction two identical masses if the distance between their centre’s half?
Gravitational Field Strength
It is the gravitational force that acts on each kilogram of a mass in the field. g= Fkg therefore the gravitational force strength of Earth is
Uniform Circular Motion
When a body moves in a circular path with a constant speed, it is said to undergo uniform circular motion. Although the speed is constant, velocity is continually changing, since it is constantly changing its direction of motion.
Centripetal
V
V
ac ac Acceleration is directed towards the centre of the circle and is therefore called “centripetal acceleration.” ac =v^2r
ac =v^2r
If T is the time taken for one revolution then: V = 2πrT ac =v^2r = (2πrT)^2r = 4π^2r^2T^2r
= 4π^2rT^2
Let us work with ac against T^2 on graphs.
Note:
Frequency is the number of revolutions completed per seconds. Cycles/seconds
Centripetal Force
… is the force responsible for centripetal acceleration. Hence the centripetal force may be defined as the force directed towards the centre of the circular path responsible for restraining the object to undergo uniform circular motion.
Fc= m.v^2r
Example
A car of mass 1.20X10^3 kg is rounding a curve of radius 1.55X10^3m at a speed of 25.0m/s/
Find: 1. The centripetal acceleration. 2. the centripetal force
ac =v^2r
Non-Uniform Circular Motion Vertical Circle Resultant force toward the centre is
FNET = FC= mv2r Top: mv2r = mg + Tension Bottom: mv2r = tension - mg
Universal Law of Gravitation
Everybody in the universe attracts every other body in the universe with a force that is proportional to the product of their masses, and inversely proportional to the square of the distance between them. This force acts along the line joining the two masses.
G is called the universal gravitational constant, and its value is 6.67 X 10-11
Eg.
What happens to the forces of attraction two identical masses if the distance between their centre’s half?
Gravitational Field Strength
It is the gravitational force that acts on each kilogram of a mass in the field. g= Fkg therefore the gravitational force strength of Earth is