Warm Up • A 10 kg block is going to be placed on a incline plane with an angle of

inclination of 40. Will it start sliding down?

Warm Up Two blocks of mass m = 2 kg and M = 5 kg are hanging off a single pulley, as shown. Determine the acceleration of the blocks. Ignore the mass of the pulley

Physics HonorsC –Day

11/16-11/17Centripetal Force

Circular Motion

What is circular motion?• a movement of an object along the circumference of a circle or

rotation along a circular path. It can be uniform, with constant angular rate of rotation. • there must be an inward force acting upon it in order to cause its

inward acceleration

The tangential velocity • The instantaneous linear speed of an object directed along the

tangent to the object’s circular path• Think of it like the velocity that the object would take if you were

spinning an object and the rope broke

• The magnitude of is constant, but the direction is changing

t

Centripetal accelerationSince , the tangential velocity, is changing because the direction is changing it must be acceleratingCentripetal acceleration

Centripetal Force• Newton’s 2nd Law states if an object, with a mass, is accelerating than

a Force must be acting on the object.

Centripetal Force• So what keeps the water in the bucket?• What keeps these kids on the wall?

Inertia

Centripital Force with Gravity

Example Problem• A 2 kg rock tied to a string is traveling at a constant speed of 4 m/ s in

a circular radius of 1.5 m. Calculate the Tension in the string. What is the direction of the centripetal force?

Example Problem• A 1500 kg car is rounding a curve with a radius of 30 m. If the

coefficient of static friction between rubber and the wet road is 0.7, what is the fastest velocity the car can drive and safely make the turn?