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