Forces and Motion 2013 M.B. Pardington, BPS

PART 1

A force is a… PUSH PULL

A force can change the motion of an object. DIRECTION SPEED

A force can change the motion of an object.

An additional force in the same direction increases the speed of the object. Push Push + Push

An additional force in the same direction increases the speed of the object. Push Push + Pull

An additional force in the same direction increases the speed of the object. Pull Pull + Pull

Definition of Balanced Forces (add this to your paper ) are two forces acting in opposite directions on an object, and equal in size. Anytime there are balanced forces on an object, the object stays still or continues to move at the same speed and in the same direction.

Opposing forces of equal magnitude acting on an object produce no change in motion. 5 N vs. 5 N Cart doesn’t move.

Opposing forces of equal magnitude acting on an object produce no change in motion. 5 N vs. 5 N Cart doesn’t move.

Definition of Unbalanced Forces (add this to your paper ) are two forces acting oppositely on an object, unequal in size, so they cause a change in the motion of an object.

NET FORCE 2 N PUSH to the RIGHT Opposing forces of unequal magnitude acting on an object result in a change in motion. NET FORCE 2 N PUSH to the RIGHT 3 N Pull + 5 N Push

NET FORCE 2 N PUSH to the RIGHT A change in motion is described as a change in speed and/or direction of an object. NET FORCE 2 N PUSH to the RIGHT 3 N Pull + 5 N Push

Forces must be balanced in order to achieve constant speed. BALANCED FORCES Forces must be balanced in order to achieve constant speed.

UNBALANCED FORCES Forces must be unbalanced (nonzero net force) in order for an object to change speed and/or direction. 20 N 40 N

UNBALANCED FORCES A force must be unbalanced (nonzero net force) in order for an object to change speed and/or direction. 30 N 20 N 50 N

UNBALANCED FORCES A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

UNBALANCED FORCES A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

UNBALANCED FORCES A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

Speed is the ratio of distance covered per unit of time. Speed = distance / time The cart moved 6 meters per 3 seconds

Speed The cart moved 6 meters per 3 seconds Mathematically, that’s 6 / 3 or 6 ÷ 3 which equals 2. The cart moved 6 meters per 3 seconds So, the cart moved 2 meters per second or 2 m/sec

PART 2

FORCE NON-CONTACT CONTACT

Contact Force

A contact force is a push or pull that directly touches the object..

Friction WATER AIR OBJECTS Friction is a contact force exerted between objects such as: WATER AIR OBJECTS

Non-Contact Forces MAGNETISM GRAVITY ELECTRICAL CHARGES

These are pushes and pulls Non-Contact Forces These are pushes and pulls from a distance.

Gravity Gravity is a force of attraction between any mass and the matter near it. The larger the mass of an object, the greater the gravitational force it exerts on other objects. For objects on Earth, the pull of the Earth is the strongest force acting on them.

Gravity “Jupiter is the most massive planet in our Solar System and; therefore, the gravity of Jupiter is the most intense in the Solar system. Its gravitational pull is 2.5 times what is here on Earth.” http://www.universetoday.com/15110/gravity-of-jupiter/

Gravity

Magnetism S S N N Here are “like” poles. Are they showing an attraction or are they repelling?

Magnetism N S S N Magnetic Repulsion They are repelling.

Magnetism N S N S Here are “unlike” poles. Are they showing an attraction or are they repelling?

They are showing an attraction. Magnetism N S N S Magnetic Attraction They are showing an attraction.

They pull and push without contact. Magnetism N S N S S S N N The attracting and repelling magnetic forces illustrate non-contact forces. They pull and push without contact.

Check out these examples of magnetic pushes and pulls: * See the side of the box for examples of how to use this device.

Check out these examples: * Do not place the hourglass on magnet if the bottom is full. Place Hourglass on magnet with the filings in the top bubble.

Check out these examples:

Check out these examples:

Wind Sock Demonstration Electrical Charges push pull Wind Sock Demonstration

They pull and push without contact. Electrical Charges The attracting and repelling electrical forces illustrated in the wind sock demonstration show non-contact forces. They pull and push without contact.

Bibliography http://powerup.ukpowernetworks.co.uk/media/22576/78.jpg http://www.clipart.dk.co.uk/DKImages/science/image_science010.jpg http://www.clipart.dk.co.uk/DKImages/science/image_science009.jpg http://www.universetoday.com/15110/gravity-of-jupiter/ http://www.mikecurtis.org.uk/images/friction.jpg http://lvp.lockyersmid.dorset.sch.uk/pluginfile.php/3230/mod_resource/content/0/content/pictures/physical/keyideas/phpkey0005.jpg http://www.united-states-flag.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/F/L/FLGBDEC1000003637_-00_st-patricks-wind-sock_4.jpg