November 26, 2012

Physics: Review & New

Also known as The Law of Inertia

Main Idea: an object needs a force to stop moving or start moving

Inertia: the ability to resist motionMore mass = more inertia (takes more force to

make its movement change)

Newton’s First Law

Also known by its math formula: F = ma

Main Idea: If you apply a force to an object, the object will move in the direction of the forceExample: if you kick a soccer ball forward, the

ball will move forward

Remember your F=ma triangle when solving for any of the variables!

Newton’s Second Law

For every action, there will be an equal and opposite reaction

If the forces are equal, there is no motion

If the forces are unequal, the object will move in the direction of the bigger force

Newton’s Third Law

Examples of Newton’s Third Law

On your paper, give me one example for each of Newton’s Laws.

For full credit you must:1. Write the definition of the law2. Give me one example3. Tell me why your example is just like the law

you are describing.4. Doodle a picture and use arrows to really

prove to me that you know it!

Give me 3! Homework Grade

Acceleration is: speeding up, slowing down, or changing direction

Speed: is traveling a distance over time (do you hear the fraction in that?)

Velocity: speed with a direction (tells you which way to goCan be specific: East, NE, South, SE, etcCan be a general direction: Up, down, left,

right

Motion & Acceleration

If the force is the same , but the object’s mass is different(the 100g weight hanging off the table for all

trials)The acceleration will decrease as the mass of the

object increasesThe car went slower as we added more mass to the

car

If the force is different, but the object’s mass is the same

(the car was always 100g)The acceleration will increase as the force

increasesThe car went faster as we increased the amount of

weight on the end of the string

Mass & Acceleration

Independent Variable: what you change; only 1 IV; X axis

Dependent Variable: what happens; what you measureY axis

Control: everything that was kept the same to make sure you were only testing one thingDo not graph the controls

Graphing Speed, Distance, and Time

Put your name, date, and period on a note card

A new student has come to our class and has never graphed before. On your note card, write the new student the directions on how to make a graph.

For full credit:1. Dry Mix2. Labeling axis3. Example of when you graphed data

Prove it. Homework Grade

Potential: stored energy (not moving)

Kinetic: energy of motion (moving)

Law of Conservation of EnergyEnergy can change from one form to anotherEnergy is neither created nor destroyed

Forms: Chemical, thermal, mechanical, electrical, light, and sound

Energy

A force that tends to oppose motion between objects that touch each other

Friction causes heat

3 types: static, rolling, and sliding

Friction

Using a force to move an object over a distance in the direction of the force

Work

W = FdTriangle Time!

Work

W

F DNewtons Meters

Joules