Text P409-413. Mass and Inertia The universe consists of matter in motion The universe consists of...

Text P409-413

Mass and Inertia

The universe consists of matter in motion

The universe consists of matter in motion

The greater the mass the harder it is to move. And . . .the harder it is to stop moving.

The greater the mass the harder it is to move. And . . .the harder it is to stop moving.

Lower mass objects are easier to move . . .and to stop moving.

NEWTON’s Laws 1st Law of Motion : 

NEWTON’s Laws 1st Law of Motion : 

 An object remains at a

in a ,until a net force acts on it.

An object remains at a

in a ,until a net force acts on it.

constant speed straight pathconstant speed straight path

An object willremain at a

constant speed (unless

disturbed).

NEWTON’s 1st Law of Motion is the law of

Higher mass higher momentumHigher velocity higher momentum

Momentum = mass x velocity

includes velocity. So, it has direction. Momentum points in the direction of motion.

Conservation of momentumWhen objects collide, all of the momentum goes somewhere.

Conservation of momentumWhen objects collide, all of the momentum goes somewhere.

Conservation of momentumWhen objects collide, all of the momentum goes somewhere.

Conservation of momentumWhen objects collide, all of the momentum goes somewhere.

NEWTON’s2nd Law of Motion :

   An object that

has a force acting on it will change its speed (accelerate).

Net force is the total amount of Force (minus the forces that cancel each other out). Force of gravity

Force of muscles

Net force

When the net force is Zero.-> NO movement

When the net force is NOT Zero.-> movement

When the net force is Zero.-> NO movement

When the net force is NOT Zero.-> movement

2 Kg ?

Static Equilibrium Balanced forces

When all forces are balanced. The net force is Zero. There is NO movement.

Static Equilibrium Balanced forces

When all forces are balanced. The net force is Zero. There is NO movement.

3 Kg

50 N

100 N

100

N50 N

50 N

50 N

NEWTON’s 3rd Law of Motion:  

For every action there is an equal and opposite reaction.

NEWTON’s 3rd Law of Motion:  

For every action, there is an equal and opposite reaction.

NEWTON’s 3rd Law of Motion:  

For every action, there is an equal and opposite reaction.

Balanced or unbalanced?Action

Reaction

Gravity Inertia FrictionGravity Inertia Friction

A car is traveling down a hill. Which of the following will affect the amount of energy the car has?

how long the car is

the time of day

how much the car weighs

the color of the car

Friction  the resistive force that occurs

when two surfaces travel past each other.

causes physical deformationgenerates heat

Friction  the resistive

force that occurs when two surfaces contact each other.  

Oliver the dog doesn't want to walk in the rain. He can make his owner pull harder on the leash to

get him out the door by

sitting on the vinyl floor. sitting on the tile floor.

sitting on the carpeted floor. sitting on the wood floor.

terminal velocity gravity will accelerate an object until air resistance (friction) does not allow it to go any faster.

In the absence of air resistance, which of these objects will fall at the fastest rate when dropped?

the ball with a mass of 75 kg

the ball with a mass of 25 kg

the ball with a mass of 10 kg

They all fall at the same rate.

Gravitational force

Gravitational force

Gravitational forceo INCREASES with Masso DECREASES with Distance

All objects in the universe are attracted to each other by the force of

effort.

friction.

gravity.

inertia.

THE END

• Do Q 1-7, P413

Four pairs of objects have the masses shown below. If the objects in each pair are the same distance apart, the gravitational force between the objects in which pair is greatest?

1 kilogram and 1 kilogram

1 kilogram and 2 kilograms

2 kilograms and 1 kilogram

2 kilograms and 2 kilograms

Four pairs of objects have the masses shown below. If the objects in each pair are the same distance apart, the gravitational force between the objects in which pair is greatest?

1 kilogram and 1 kilogram

1 kilogram and 2 kilograms

2 kilograms and 1 kilogram

2 kilograms and 2 kilograms

Simple Machines and work

Lever Inclined plane Pulley Wedge Screw Wheel and axle

Simple Machines and work

Lever Inclined plane Pulley Wedge Screw Wheel and axle

Simple Machines• Pulley• Wheel &

Axle• Lever• Inclined plane• Screw• Wedge• Gear

Simple MachinesSimple MachinesPulley

Wheel & Axle

Lever

Pulley

Wheel & Axle

Lever

Inclined plane

Screw

Wedge

Gear

Inclined plane

Screw

Wedge

Gear

Which activity involves the use of a simple machine?

riding on a seesaw

flying a kite

listening to a radio

skiing down a hill

Simple MachineSimple Machine

A mechanism that lowers the amount of force needed to do work, by increasing

the distance.

A mechanism that lowers the amount of force needed to do work, by increasing

the distance.

On which simple machine is a fulcrum found?

pulley

wheel

axle

lever

Which of the following is often used as a lever?

file

nail

saw

crowbar

The WedgeThe Wedge

The bottom of this light bulb is an example of what type of simple machine?

a lever

a pulley

a screw

a wedge

What type of simple machine is used to split things apart?

screw

wheel and axle

wedge

inclined plane

What type of simple machine is used to pull a flag up to the top of a flagpole?

screw

wheel and axle

inclined plane

pulley

Centripetal force The inward force on a spinning object,that stops it from going in a straight line.

Perpendicular

Centripetal force

Centripetal force The inward force on a Spinning object.

Centripetal force The inward force on a Spinning object.

Centripetal force The inward force on a Spinning object.

Centripetal force The inward force on a Spinning object.

Satellites stay in place as they orbit because of . . .

the repeated firing of rocket boosters.

the gravitational pull of Earth.

a narrow path through the vacuum of space.

solar panels generating energy to hold them in place