Boulders do Boulders do not move not move without without cause.cause.

GGEORGIAEORGIA PPERFORMANCEERFORMANCE SSTANDARDSTANDARDS

SP1:SP1: Students will analyze Students will analyze the relationships between the relationships between force, mass, gravity, and force, mass, gravity, and the motion of objects.the motion of objects.d.d. Measure and calculate Measure and calculate the magnitude of frictional the magnitude of frictional forces and Newton’s three forces and Newton’s three laws of motion.laws of motion.

Essential Question 3.3:Essential Question 3.3:

►► Ultimately, what is Ultimately, what is the the source of friction?source of friction?

3.3 Galileo on Motion3.3 Galileo on Motion Galileo argued that Galileo argued that only when friction is only when friction is present –as it usually is– present –as it usually is– is a force necessary to is a force necessary to keep an object moving.keep an object moving.

3.3.13.3.1 Friction: the Friction: the force that acts force that acts between materials between materials that touch as they that touch as they move past each other.move past each other.

3.3.23.3.2 Friction is Friction is caused by caused by irregularities in the irregularities in the surfaces of objects surfaces of objects that are touching.that are touching.

3.3.33.3.3 If friction were If friction were absent, a moving absent, a moving object would object would needneed nono forceforce whatever to whatever to remain in motion.remain in motion.

Galileo based his Galileo based his conclusions on conclusions on experimental experimental

evidence.evidence.

When the ball rolls downward, When the ball rolls downward, it moves with Earth’s gravity, it moves with Earth’s gravity,

and its speed increases.and its speed increases.

When the ball rolls upward, it When the ball rolls upward, it moves against gravity and moves against gravity and

loses speedloses speed

When the ball rolls on a level When the ball rolls on a level plane, it does not move with plane, it does not move with

or against gravity.or against gravity.

The ball rolling down The ball rolling down the incline rolls up the the incline rolls up the opposite incline and opposite incline and

reaches its initial height reaches its initial height

As the angle of the upward As the angle of the upward incline is reduced, the ball rolls incline is reduced, the ball rolls

a greater distance before a greater distance before reaching its initial height.reaching its initial height.

If there is no friction, the ball If there is no friction, the ball will never stop unless it hits will never stop unless it hits

something.something.

3.3.43.3.4 Galileo stated Galileo stated that the tendency of a that the tendency of a moving body to keep moving body to keep moving is a natural moving is a natural tendency.tendency.

3.3.53.3.5 Every material Every material object resists change object resists change to its state of motion.to its state of motion.

3.3.6 3.3.6 The property of a The property of a body to resist changes body to resist changes to its state of motion to its state of motion is calledis called inertiainertia..

CONCEPCONCEPTTCHECCHECKK

According to Galileo, According to Galileo, when is force needed when is force needed to keep an object to keep an object moving?moving?

Galileo argued that only Galileo argued that only when friction is when friction is

present is a force present is a force needed to keep needed to keep

an object moving an object moving

Law of inertiaLaw of inertia

Law of InertiaLaw of Inertia

Essential Question 3.4 :Essential Question 3.4 :

►► Is a constant force Is a constant force reallyreally necessary to necessary to keep an object keep an object

moving?moving?

3.4 Newton’s Law of 3.4 Newton’s Law of InertiaInertia

Newton’s first law Newton’s first law states that every object states that every object continues in a state of continues in a state of rest, or of uniform rest, or of uniform speed in a straight line, speed in a straight line, unless acted on by a unless acted on by a nonzero net force.nonzero net force.

3.4.13.4.1 Objects in a Objects in a state of rest tend to state of rest tend to remain at rest. Only a remain at rest. Only a force will change that force will change that state. state.

3.4.23.4.2 In the absence of In the absence of forces, a moving forces, a moving object tends to move object tends to move in a straight line in a straight line indefinitely.indefinitely.

3.4.3 3.4.3 A force is only A force is only needed to (1) needed to (1) overcome any friction overcome any friction that may be present that may be present and (2) to set objects and (2) to set objects into motion initially.into motion initially.

Essential Question 3.5 :Essential Question 3.5 :

►► Why is it commonly Why is it commonly said that “inertia is said that “inertia is

a a property of property of matter”?matter”?

3.5 Mass- A Measure 3.5 Mass- A Measure of Inertiaof Inertia

The more mass an The more mass an object has, the greater object has, the greater its inertia and the its inertia and the more force it takes to more force it takes to change its state of change its state of motion.motion.

3.5.13.5.1 Mass is the Mass is the quantity of matter in quantity of matter in an object. Mass is a an object. Mass is a measure of the inertia measure of the inertia in an object.in an object.You can tell You can tell

how much how much matter is in a matter is in a can when you can when you kick it.kick it.

3.5.2 Mass is measured in the fundamental unit of kilograms.

The standard The standard kilogram is kilogram is housed at housed at the the International International Bureau of Bureau of Weights and Weights and Standards Standards near Paris. near Paris.

3.5.33.5.3 A large mass A large mass does NOT mean a does NOT mean a large volume.large volume.

The pillow has The pillow has a larger size a larger size (volume) but a (volume) but a smaller mass smaller mass than the than the battery.battery.

3.5.43.5.4 WeightWeight is the is the force of gravity on an force of gravity on an object. Weight object. Weight depends on an depends on an object’s location – object’s location – mass remains mass remains constant regardless of constant regardless of location (location (unless, of unless, of course, matter is course, matter is removed or addedremoved or added.).)

3.5.53.5.5 Mass and weight Mass and weight are are proportionalproportional to to each other, but they each other, but they are are not not equal to each equal to each other.other.

3.5.63.5.6 MassMass has to do has to do with the with the amountamount ofof mattermatter in the object, in the object, while while weightweight has to do has to do with how strongly that with how strongly that matter is attracted by matter is attracted by gravitygravity..

3.5.73.5.7 One kilogram One kilogram weighs 10 newtons.weighs 10 newtons. The SI units of mass is The SI units of mass is the kilogram – the kilogram – about about 2.2 pounds2.2 pounds. The SI . The SI unit of force is theunit of force is the newton (N)newton (N)..

One kilogram One kilogram of nails weighs of nails weighs 10 N, which is 10 N, which is equal to 2.2 equal to 2.2 poundspounds

1010NN

3.5.83.5.8 Weight = mass x Weight = mass x gravitygravity kg x kg x

mm ss22

kgkg mmss22