Motion

Equations

N EWTON ’ S LAWS OF MOTION First law: law of Inertia a body at rest remains at rest and a body in motion continues to move in straight line at constant speed, unless an external unbalanced force acts on it. AB A=B External forces No movement rotate A=B Unbalance force

Second law: Law of Acceleration an external unbalance force acting on an object produces an acceleration in the direction of the net force, an acceleration that is directly proportional to the unbalanced force and inversely proportional to the mass of the body Where: F=force m=mass a= acceleration Where: w = weight m = mass g = gravity

Third law: Interaction for every force that a first body exerts upon second body, there is a force equal in magnitude but opposite in direction that a second body exerts upon the first body.

A 100N box is sliding down a frictionless plane inclined at an angle of 30° from the horizontal. Find the acceleration of the box. a=? Note: N is always ┴ to the plane 30° N F W FBD- free body diagram- shows all the forces acting on the object

Solution:

U NIFORM CIRCULAR MOTION - motion of an object in a curved or circular motion 10 rev. in 5s Frequency, F = the no. of revolution per unit time

Period, T = the time required for one complete revolution. Where: v= linear velocity r= radius Radian- angle subtended by the arc of a circle whose length is equal to the radius of the same circle. r x

Where: v= linear velocity r= radius ω =angular velocity Where: ω = angular velocity = angle turned through t = time elapse Using linear velocity if Using angular velocity Centripetal force

S AMPLE PROBLEM If the radius of the circular path of the stone is 0.5m and its period is 0.5s. What is its constant speed? Given: r= 0.5m T= 0.5s Required : v=? Solution:

What is the angular velocity of a stone which makes 10 rev in 5 seconds? The radius of the circular path is 0.5m Given: no. of revolution = 10 T= 5s r=0.5m Required: ω=? Solution:

A mass of 0.5kg is whirled in a horizontal circle of radius 2m. If it makes 5 rev in 5s Find: a. speed b. acceleration c. centripetal force Given: m=0.5 kg r=2m t=5s rev=5 T=1s

Solution:

End of presentation