This document discusses different types of forces including thrust, lift, drag, magnetism, gravity, and friction. It explains how balanced and unbalanced forces affect the motion of objects. Balanced forces cause objects to remain stationary, while unbalanced forces cause movement, changes in speed or direction. Friction is defined and different types are described including static, rolling, sliding, and fluid friction. Examples are given of how forces and friction impact various situations and technologies.

1. Forces

2. Types of Forces Thrust Lift and Drag Magnetism Push Pull Gravity

4. Stop moving

6. Slow down

8. Balanced Forces Each sumo wrestler is applying equal pushing force, resulting in them remaining stationary

9. Balanced Forces The downward for of gravity is equal to the lifting force of the air under the wings, resulting in the aircraft remaining aloft

10. Balanced Forces The ship is floating on the water, the forces are balanced. Gravity is pulling the ship downward, but the water is forcing the ship upwards due to its displacement of lesser density

11. Equal and Opposite Forces If substances are sufficiently strong, they can not be moved when forces are applied, because they will act in an equal and opposite manner

12. Equal and Opposite Forces In the case of the balancing rocks, the upward force of the lower rocks make up for the downward force of gravity While the balloon pulls upward, the child’s hand pulls downward

13. Equal and Opposite Forces In addition, the forces being applied by gravity can overcome upward forces, with sometimes unfortunate results

14. Equal and Opposite Forces If substances are sufficiently strong, they can not be moved when forces are applied, because they will act in an equal and opposite manner

15. Unequal Forces Those unequal forces will cause movement whether it is horizontal or vertical

16. Unequal Forces If upward thrust or lift exceeds the force of gravity, the spaceship or aircraft will take off.

17. Unequal Forces Drag In sky diving, initially gravity far exceeds drag, and thus you free fall very rapidly (over 100 mph). Once the chute is released, the amount of drag increases dramatically and you slow to under 10 mph

18. Unequal Forces Using drag and lift, wingsuit flyers and paragliders can control where they go and soar around for long periods before eventually landing.

19. Unbalanced Forces The magnetic attractive force is pulling the metal upwards The magnetic force is greater than the force of gravity therefore the metal can be lifted up Gravity is pulling the metal to the ground

20. Unbalanced Forces The magnetic repulsive force is pushing the train upwards The magnetic force is greater than the force of gravity therefore the train can be levitated Maglev technology has potential, because the train is not physically in contact with the track. It hovers and thus there is no friction Gravity is pulling the metal to the ground

21. Balanced and Unbalanced Forces The rubber band is exerting an opposite force to the person pulling on it. It will remain in this state until one of two things happen: The material snaps (pulling force exceeds material strength) Person releases force and rubber band rebounds and launches

22. FRICTION Friction occurs when two substances are in contact with each other The greater the friction, the more force must be applied to move 24 mph 35 mph 5 mph

23. What is friction? Friction is a force that acts when two objects rub together. When the two objects appear to be smooth, there is less friction. When the two objects are rough, there is a greater amount of friction.

24. Friction Road bikes have tiny thin wheels to reduce contact with the ground and friction. In addition, the bikers wear tight fitting clothing to reduce air friction. Mountain bikes have thicker tires to increase contact with the ground, using friction to prevent the biker from slipping and falling in rough terrain.

25. “Friction-less Movement” Some things can be done to reduce friction. Using lubrication such as water or oil can reduce the contact between solid surfaces Air hockey uses air to lift the puck up and allow it to travel rapidly.

26. Friction at the Microscopic Level Even though some objects look smooth, microscopically they are very rough & jagged. As they slide against each other they grind and drag against each other. Flies use microscopic hairs on their feet to grip these jagged edges on the surfaces

27. Different types of Friction: Static Friction: Objects not moving.

28. Different types of Friction: Rolling Friction: Round objects rolling.

29. Different types of Friction: Sliding Friction: Objects moving.

30. Different types of Friction: Fluid Friction: Force through fluids or air. When it is through air it is called air resistance.

31. Fluid Friction In this case, the waterfall is encountering air resistance on the way down, causing it to spread out and slow down. It also experience friction upon striking the pool surface, causing it to splash and spread.

32. Friction is good… Without friction we wouldn’t be able to walk, sit in a chair or drive safely. Everything would keep sliding and falling over. We need friction between our feet and the ground or we would not be able to stand up. When you are riding a bike and press the brakes, friction slows your bike down.

33. Friction is bad… If you want to push something heavy, friction makes it harder to move. Friction produces heat. Causing heat to build up is not always a good thing, especially inside a car engine. We try to reduce the amount of friction in a car engine by adding oil.

34. Gravity The attractive force between all objects in the universe

35. The greater the mass, the more gravity it has Gravity