FORCE = Any push or pull which causes something to move or change its speed or direction

Forces can be BALANCED or UNBALANCED Balanced forces are equal in size and opposite in direction Un Unbalanced forces are not equal in size and/or opposite in direction. If the forces on an object are UNBALANCED, we say a NET force results.

Can you think of examples of forces? Balanced Forces? Unbalanced Forces?

1) What famous physicist are units of force named after? 2) What does velocity measure? 3) If Moby has a mass of 50 kg and Tim has a mass of 40 kg, who would require more force to move?

GRAVITY GRAVITY: An attraction force between all masses Newton’s universal law of gravitation Newton’s universal law of gravitation: Every object in the universe exerts a gravitational attraction to all other objects in the universe The amount of gravitational force depends upon the mass of the objects and the distance between the objects

force The greater the mass, the greater the force distanceless The greater the distance, the less the force Acceleration due to gravity = 9.8 m/s/s or 9.8 m/s 2

Weight is a measure of the gravitational force between two objects The greater the mass the greater the force (weight) Measured in units called Newtons (N)

1) How does the gravity on the moon compare to the gravity on Earth? 2) Why don’t you notice your own gravitational pull on the Earth? 3) On what two things does the force of gravity depend?

Motion: A change in position of an object compared to a reference point Motion involves all of the following:

Speed The rate of change in position Speed = distance ÷ time or = distance time

Velocity Speed plus direction Example: 50 km/hour north Speed vs. Velocity

Acceleration The rate of change in velocity Positive acceleration = speeding up Negative acceleration = slowing down (decelerate) Acceleration = V final – V initial / Time or = ∆Velocity Time

1.Which graph represents a car at “0” velocity? 2.Which graph represents positive acceleration? 3.Which graph represents constant speed?

1) What units are used to measure speed? 2) What units are used to measure acceleration? 3) What is another way to say “slowing down” in terms of acceleration?

Friction = A force that opposes or slows down motion Caused by the physical contact between moving surfaces The amount of friction depends upon the kinds of surfaces and the force pressing the surfaces together Changes motion into heat

What are some ways athletes uses friction? MythBusters FrictionFriction

Inertia A property of matter The tendency of an object to resist any change in its motion The greater the mass the greater the inertia The greater the speed the greater the inertia

 Energy can change forms.  Energy cannot be created or destroyed.

There are 2 states of energy:  Potential  Kinetic

Stored Energy

 The energy of motion  The faster the object moves, the more kinetic energy. Sing Along

 The tendency of an object to resist any change in its motion.  If motionless, it tends to remain at rest.  If moving, it tends to keep moving at the same speed and in the same direction. Demo

 The transfer of energy through motion.  When a force acts over a distance in the direction of an object’s motion.  Work = force x distance  W = F x d  Work is measure in Joules