Fri Oct 12

AttendanceHomeworkTorqueSHMSprings

pg 313 Problems (Google Docs)pg 446 Problems (Google Docs)

What have we studied so far?

GP 1

VectorsSOHCAHTOA1D KinematicsProjectiles (2D Kinematics)

Relative MotionForcesFBDFriction

GP 2

WorkEnergy TypesEnergy ConservationPowerStopping DistanceMomentumCollisions

ImpulseCircular MotionTorqueSHMSpringsPendulumGravitation

Torque

What is torque?

How do you spin things to make things go in and out?

Opening a doorWhat’s the easiest way?

Formula for torque

What is the torque for a wrench that is 15 cm long and you pull with a force of 20 N?

What is the difference in torque if you were to change the angle to 45 degrees?

Balancing weights on a meter stick

If the fulcrum is placed at 20 cm, a 1 kg mass is placed at the close end, where should a 0.3 kg placed to balance it out?

A wheel at 2 strings connected to it. One string is attached at a radius of 30 cm and another at 50 cm. The first string pulls at an angle of 90o and the second at an angle of 30o. If each string has a force of 50 N, what is the total torque?

A 100 m bridge has 2 columns supporting it at the ends. If a 2500 kg car is in the middle and another car of 3000 kg is at 75 m, what are the forces in the supports?

Mass and Springs Simulation

What do you notice about the amount that the springs stretch?

What happens to the speed and amount of stretch when different masses are used?

What is SHM?

Springs

Finding the spring constant

When a family of 4 people with a total mass of 200 kg step into their 1200 kg car, the springs compress 3 cm.What is the spring constant?How far will the springs compress if the car is loaded with 300 kg?

Motion with a SHO

A spring stretches 0.15 m when a 0.3 kg mass is hung from it. The spring is then stretched another 0.1 m from this equilibrium point and released.What is the spring constant?What is the amplitude?What is the max velocity?What is the speed when the mass is 0.05 m from the equilibrium point?What is the max acceleration?

Frequencyf = 1

 T

Period T = 1 f

Period of SHM

T = 2p m  k

F = 1 = 1 k T  2p m

What is the period and frequency for the car from before?

A small insect of mass 0.3 g is caught in a spider web of negligible mass. The web vibrates with a frequency of 15 Hz.

What is the spring constant?

What would be frequency be if the insect had a mass of 0.1 g?

What have we studied so far?