QOD#48 D What does each line represent? A – B – C – D – B C A Distance Acceleration (speeding up) Stopped – no motion C A Constant Speed deceleration (slowing down) Time

Forces Force – a push or pull on an object. Unit – Newtons (N)

Types of Forces Contact forces ________________ - a force that is applied when two objects touch. 1. Push ex: 2. Pull

Friction Air resistance Buoyancy 3. ___________________ - the resistance between two surfaces that are in contact with each other (sliding against each other). ex: 4. ___________________ - the force exerted on an object by the air as its moving. (drag force) 5. ___________________ - the upward force exerted by a fluid, which opposes the weight of an object. Air resistance Buoyancy

Non-Contact Force Magnetic Force Electric Force Gravitational Force B. ____________________ - a force that one object applies to another object without touching. 1. ____________________ ex: 2. ____________________ (includes static electricity) 3. ____________________ Magnetic Force Electric Force Gravitational Force

Gravity Lift Thrust (push) Drag (air resistance) Gravity Buoyancy

Forces WS

Measuring Force Force is measured in Newtons (N) 1 Newton = lifting a stick of butter 20 Newtons = lifting a 2-L bottle of soda

Measuring Force Activity Object Weight in Newtons (N)

QOD #49 Falling Feather & Golf Ball 1. What happens when we drop a golf ball and a feather down a stairwell? 2. Why does this happen?

Gravity Weight ________________ – the gravitational force exerted on an object. Every object (that has mass) exerts a __________________________ of attraction on any other object. gravitational force

Mass The greater the mass of two objects, the ________________ the gravitational force is between them. greater Does the earth & the person or the moon & the person have a greater gravitational force between them? Why?

Which person will feel a greater force of gravity with the earth? Distance The force of gravity increases as two objects become ____________ (as the distance between the objects ______________). The force of gravity decreases as two objects ____________________ (as the distance between the objects ______________). closer decreases move farther apart increases Which person will feel a greater force of gravity with the earth?

1. Between which two objects is there the greatest gravitational force (based on their mass)? a. b. c. 2. Between which two objects is there the greatest gravitational force (based on their distance)?

What is the speed of a giraffe if it travels 400 meters in 40 seconds? QOD#50 What is the speed of a giraffe if it travels 400 meters in 40 seconds?

Balanced/Unbalanced Forces Forces are described in terms of ___________ and ____________ (strength). direction magnitude Ex1: Pushing the box to the right 100 N Ex2: Downward gravitational force 3 N

net force The ______________ is the combination of all the forces acting on an object. Gravitational force of 15 N Ex3: Lift force of 15 N Net force: __________ 0 N Ex4: 1,050 N Net force: __________ 650 N 400 N

Ex5: 125 N 375 N 250 N Net force: __________

Balanced forces stays still Ex6: 0 N ____________________ – forces acting on any object that combine and form a net force of zero. -When balanced forces are acting on an object, the object _________________. Balanced forces stays still Ex6: 300 N 300 N Net force: __________ 0 N

Unbalanced forces motion Ex7: 100 N __________________ - forces acting on an object that combine to a net force that is not zero. -Objects go into ___________ because of unbalanced forces. Unbalanced forces motion Ex7: 400 N 500 N Net force: __________ 100 N

Balanced/Unbalanced WS