Pushes and PullsPushes and Pulls

The acceleration of an object The acceleration of an object depends on its mass and the depends on its mass and the

force applied… force applied…

TEKS 8.6C investigate and describe application of Newton’s law of force and motion such as in vehicle restraints, sports activities, amusement park rides, Earth’s tectonic plates and rocket launches

TEKS 8.6A demonstrate and calculate how unbalanced forces change the speed or direction of an object’s motion

a force is aa force is a

or or

ForcesForces may be may be applied by direct applied by direct contact, contact,

such as in such as in frictionfriction and air and air resistance or resistance or physically physically pushing or pushing or pullingpulling on an on an objectobject

OObjects that bjects that are not are not

touching touching still still exertexert a push a push or pull on one or pull on one

another.another.

Examples are Examples are gravitygravity, , electric electric forcesforces or or magneticmagnetic forces. forces.

Forces can be Forces can be represented with represented with arrowsarrows, called , called vectorsvectors that show that show the the sizesize and and directiondirection of a of a force. force.

The arrows The arrows point in the point in the directiondirection of of the force.the force.

Forces may be Forces may be measured with a measured with a spring scalespring scale in in units called the units called the

NewtonNewton. .

The arrows The arrows point in the point in the directiondirection of the of the force. force.

The combination of The combination of all forces acting on all forces acting on an object is called an object is called net forcenet force. .

Net force is Net force is found by found by addingadding forces which act forces which act in the in the same same directiondirection. .

Forces acting in Forces acting in oppositeopposite directions are directions are subtractedsubtracted. .

If the net If the net force is 0, the force is 0, the forces are forces are balancedbalanced. .

Unbalanced forces Unbalanced forces cause a change in cause a change in

motionmotion. . The object The object moves in the moves in the

direction of the direction of the greatestgreatest force. force.

Gravity Gravity

Gravity pulls objects toward the center of Earth.

The force of The force of gravity on an gravity on an

object object determines determines the object’s the object’s weightweight..

On On Earth, Earth, the the

force of force of gravity gravity is is 9.89.8

m/secm/sec22..

Your weight can Your weight can be found by be found by multiplying your multiplying your massmass in in kilograms by the kilograms by the forceforce of gravity! of gravity!

An upward An upward force, called force, called the the normalnormal force, force, pushes pushes upward on upward on objects.objects.

gravity 9.8m/s2

normal force

This force is equal to This force is equal to object’s object’s weightweight and and supports the object.supports the object.

It is It is equalequal and and opposite to the force opposite to the force of gravity. of gravity.

normal force

gravity/weight

To overcome To overcome the gravity, the gravity, the forces the forces acting on an acting on an object must object must be be unbalancedunbalanced..

normal force

gravity

30 N 80 N

NET FORCE: 50 left50 left

10 N 10 N

NET FORCE:00

15 N 5 N

NET FORCE:20 right20 right

10 N

20 N

NET FORCE: 10 down10 down

30 N

25 N

NET FORCE:5 up5 up

20 N

?

NET FORCE: 70 N down

90 N

NET FORCE: 60 N left

? 80 N

20 N

200 N

?

NET FORCE: 0 N balanced

50 N?

200 N200 N

50 N50 N

10 N

10 N

NET FORCE: 30 N right

? 20 N50 N50 N