88 Balanced and Unbalanced Forces 87 11/03/2015 Starter: Paste Starter here when done. Application/ Connection: Complete Ws. Turn in when done Exit: Think of something in your life that requires force and describe how it relates to what you learned today. 11/03/2015 Practice : Paste Notes here when done Balanced and Unbalanced Forces EQ: What forces can change the motion and speed of an object, and how are those forces used to make our world lives easier?

Starter Mrs. Hernandez brought her pet bird to school one day to find out what her students understood about forces. As the bird rested on a perch, Mrs. Hernandez asked her students to describe any forces acting on the bird. This is what some of her students said: Bob: The only force acting on the bird is gravity. Chelle: The only force acting on the bird is air pressure. Fred: There are no forces acting on the bird because the perch stops any forces from acting on it. Omar: There are many forces acting on the bird. The bird is held in place by the force of the branch. Katrina: The force of gravity pulls down on the bird while the branch pushes up to support the bird. Which student do you most agree with? Explain your thinking. What reasoning did you use to decide what forces were acting on the bird?

November 03, 2015 AGENDA 8.6 A I will be able to demonstrate and calculate how unbalanced forces change the speed or direction of an object while taking notes and doing calculations 1 Starter 2. Notes 3. Ws 4. Exit

DateLecture/ Activity/ Lab Page Table of Contents 10/22 Evidence of Chemical Reactions /23 Test and Ws /26 Chemical Reactions lab /27 Potential and Kinetic Energy /28 Speed, Velocity, and Acceleration Notes /29 Speed and Velocity Lab /30 Interpreting Graphs /2 Walking Lab II with graphing ( Representing Motion) /3 Balanced and Unbalanced Forces 87-88

Pushes and Pulls The acceleration of an object depends on its mass and the 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 a or

Forces may be applied by direct contact,

such as in friction and air resistance or physically pushing or pulling on an object

Objects that are not touching still exert a push or pull on one another.

Examples are gravity, electric forces or magnetic forces.

Forces can be represented with arrows, called vectors that show the size and direction of a force.

The arrows point in the direction of the force.

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

The arrows point in the direction of the force.

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

Net force is found by adding forces which act in the same direction.

Forces acting in opposite directions are subtracted.

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

Unbalanced forces cause a change in motion. The object moves in the direction of the greatest force.

Gravity

Gravity pulls objects toward the center of Earth.

The force of gravity on an object determines the object’s weight.

On Earth, the force of gravity is 9.8 m/sec 2.

Your weight can be found by multiplying your mass in kilograms by the force of gravity!

An upward force, called the normal force, pushes upward on objects. gravity 9.8m/s 2 normal force

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

It is equal and opposite to the force of gravity. normal force gravity/weight

To overcome the gravity, the forces acting on an object must be unbalanced. normal force gravity

30 N 80 N NET FORCE: 50 left

10 N NET FORCE: 0

15 N 5 N NET FORCE: 20 right

10 N 20 N NET FORCE: 10 down

30 N 25 N NET FORCE: 5 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 N

10 N NET FORCE: 30 N right ? 20 N 50 N

88 Balanced and Unbalanced Forces 87 11/03/2015 Starter: Paste Starter here when done. Application/ Connection: Complete Ws. Turn in when done Exit: Think of something in your life that requires force and describe how it relates to what you learned today. 11/03/2015 Practice : Paste Notes here when done Balanced and Unbalanced Forces EQ: What forces can change the motion and speed of an object, and how are those forces used to make our world lives easier?