FORCE AND MOTION UNIT 7 TH GRADE SCIENCE 2007

GLOSSARY OF TERMS POSITION The location of an object. X is the abbreviation/variable for position.

GLOSSARY OF TERMS MOTION A change in an object’s position relative to a particular reference point.

GLOSSARY OF TERMS ACCELERATION The rate of change of velocity or how quickly an object’s velocity changes. Units: m/s 2

GLOSSARY OF TERMS FORCE A measure of the amount of push or pull acting on an object. Units: Newtons (N). 1N=force needed to accel. 1kg at 1m/s 2

GLOSSARY OF TERMS FRICTION A force that OPPOSES the motion of two objects in contact. TYPES: sliding, rolling, wind resistance, drag.

GLOSSARY OF TERMS INERTIA = “laziness” Resistance to changes in motion in any object with mass. More Mass = More Inertia

FIRST LAW OF MOTION Objects in motion will remain in motion in a straight line and at a constant speed; objects at rest will remain at rest; unless the object is acted on by an unbalanced force.

FIRST LAW OF MOTION THE BIG IDEA: FORCES are the ONLY things that can overcome inertia and cause changes in motion.

FIRST LAW OF MOTION EXAMPLES: pebble in space Person in a car crash – without a seatbelt?

2ND LAW OF MOTION The acceleration (change in motion) of an object is determined by the size of the force and the mass of the object. THE BIG IDEA... Bigger masses need bigger forces to accelerate them. Bigger accelerations take bigger forces.

2ND LAW OF MOTION FORMULA: F = m x a TRIANGLE:

3rd LAW OF MOTION When one object pushes a second object with a force there is always an opposite force from the second object pushing on the first. BIG IDEA... Each action force has an equal and opposite reaction force. Forces are always “TWINS”