Jan. 12, 2015 Chapter B2: Forces, Machines, and Work P B33

Jan. 12, 2015
Chapter B2: Forces, Machines, and Work
P B33 Identifying Cause and Effect
1. Cause- a person, thing, or event that makes something
2. Effect- the result of a cause; what happens
You hit the baseball.
The baseball changes directions.
You pedal faster.
Your bike moves faster.
Lesson 1: What makes things move?
1. force- a push or a pull
2. friction- the force caused by two objects rubbing
together that slows down or stops moving objects
• Objects cannot move unless a force is applied to them.
• Force is needed to slow down, speed up, or change
• When you change the direction of force, you change the
direction an object moves.
• More force is required to move heavier objects or to
move objects faster and farther.
Jan. 13, 2015
Lesson 1: continued
• Friction occurs between two objects that are rubbing
against each other.
• Friction slows down or stops a moving object.
• Rough objects, like a rug, produce more friction than
smooth objects, like tile.
• An object will continue moving until a force is applied,
such as friction.
• Without friction people would not be able to walk or put
food on a fork.
• Friction causes heat between the objects.
Jan. 14, 2015
Lesson 2: What are gravity and magnetism?
1. gravity- the force that pulls objects toward the center of the earth
2. magnetism- the force that causes magnets to pull on objects that are
made of certain metals, such as iron
3. pole- a place on a magnet where magnetism is strongest
Without gravity, objects would float away.
Gravity pulls objects toward the earth.
The pull of gravity gives objects weight.
Weight is the measure of the pull of gravity on an object.
That is why mass and weight are different.
Jan. 15, 2015
Lesson 2: continued
• Magnets attract objects made of certain metals. The
force is called magnetism.
• Every magnet has a north and south pole.
• Magnets are strongest at the poles.
• North and south poles are on opposite sides on the
magnet. They attract each other, which means they
stick together.
• When the same poles are near each other, they repel,
or push away.
• When a magnet is hanging on a string, its north pole will
point north (like a compass).
Jan. 20, 2015
Lesson 3: How do simple machines help you do work?
p B44
1. work- something done whenever a force moves an object through
a distance
2. simple machine- one of six kinds of tools with few or no moving
parts that make work easier
3. lever- a simple machine made of a bar or board that is
supported underneath at the fulcrum
4. fulcrum- the point on which a lever is supported and moves
5. inclined plane- simple machine that is a flat surface with one end
higher than the other
6. screw- a simple machine used to hold objects together
7. pulley- a simple machine made of a wheel and a rope
8. wheel and axle- a simple machine that has a center rod attached
to a wheel
9. gear- a wheel with jagged edges like teeth
10. wedge- a simple machine used to cut or split an object
• Work is done anytime you use force to move an object.
• The amount of work depends on how much force is
needed(how big the object is) and how far the object
• Moving two puppies is more work than moving one.
• Pushing a ball two feet is less work than pushing it ten
• If an object does not move, no work was done. For
example pushing the wall is not doing work.
Jan. 21, 2015
p B46 Lesson 3: continued
• Simple machines make work easier. There are 6 types.
• A lever is made of a bar or board. It moves across a point
called the fulcrum.
• Levers help you move objects by pushing on one end.
• If you move the fulcrum closer to the object, you can lift
it more easily.
• A seesaw is an example of a lever.
• An inclined plane is made with a flat surface that is raised
on one end.
• Ramps are inclined planes.
• A slide and a hill are examples of inclined planes.
• A screw is an inclined plane wrapped around a rod.
• Screws hold things together.
Jan. 22, 2015
p B48 Lesson 3: continued
• A pulley is a rope or chain that is wrapped around a
• A pulley helps to move objects up and down.
• We use a pulley to raise the flag and raise blinds up or
• A wheel and axle is made by a rod attached to a wheel.
• A wheel and axle can help move heavy objects.
• Skates, wheel on a car, and a wheelbarrow are all
• A gear is a type of wheel with teeth.
• They can help things turn and move.
• A watch and a bicycle both have gears.
• A wedge is made of two inclined planes together.
• A wedge can split things apart.
• Knives and axes are examples of wedges.
• Animals use parts of their bodies as simple machines.
• A rabbit uses its claws as wedges and its hind feet as
shovels, or levers, to dig through the dirt.
• A bird uses its beak as two levers fastened together to
pick things up.
• Beavers use their long teeth as a wedge to cut wood.