2. Forces in Action What is motion? Motion is movement. Example: moving in a car. Motion is a change in position relative to a stationary reference point.

3. What is Speed? Speed is the rate of motion. Speed = distance time Distance refers to positions (starting point to ending point) Time is a way to separate “then” from “now”. It is a measure of “how long” something takes to happen. (start to finish)

4. Velocity and Acceleration VelocityVelocity = is a speed in a given direction. Example: 50 mph North to the school AccelerationAcceleration = a change in velocity. Example: a car at a stop sign or a car turning.

5. Changes in motion are due to forces ForceForce = a push or a pull. Example: push of a hand; pull of gravity

6. What is a Force? A f ff force is a p pp push or a p pp pull.

7. What is inertia? Inertia = the tendency to resist changes in motion. Example: motion and seatbelts

8. Mass and Inertia Mass and Inertia “The bigger they come the harder they fall”

9. What is mass? MassMass = the amount of matter that an object has. It is also a measure of an object’s inertia – how it resists changes Weight Weight = force of gravity on your mass

10. Newton’s Laws of Motion Sir Isaac Newton Presented three laws of motion

11. Newton’s 1st Law of Motion An object at rest remains at rest, an object in motion remains in motion unless acted upon by an outside force. Note: Relate back to penny activity

12. Interactions that push or pull GravityGravity = a force pulling objects toward the center of the Earth (9.8 m/s2). All objects accelerate to the Earth at the same rate unless air resistance slows them down. FrictionFriction = an interaction that resists motion. Example: walking on ice vs walking on sticky surface. –No friction vs lots of friction, –Need more friction vs need less friction

13. Activity: Is friction a force? Add in the force lines for gravity. In order to achieve motion what forces must be overcome by the pusher? How much force must be applied to move the block?

14. Balanced and Unbalanced Forces

15. Balanced force = forces acting on the object cancel each other out. Example: seat, book. No accelerating.

16. Unbalanced force Unbalanced force = a greater force is acting on an object in some direction. This produces motion. Force

17. Newton’s Second Law The change of an objects momentum is proportional to, and in the same direction as, the force acting on the object.

18. Action and Reaction Forces Action force: is when you push or pull objects. Reaction force: the force that pushes back on you.

19. How forces act on objects Newton’s 2nd Law: F = M x A Force = mass times acceleration Acceleration, mass and force

20. Newton’s Third Law For every action there is an equal, opposite reaction. “I pull on it, it pulls on me”

21. Pressure Pressure = a force per unit area. F P = A Pressure = force divided by area

22. Pressure in Fluids Fluid = anything that flows (gases, liquids) –M–Movement in fluids is due to pressure changes. –M–Movement is from high to low pressure.

23. What is buoyancy? Buoyancy is floating. Buoyant force Buoyant force = the upward force exerted by water. Buoyant force is why objects feel lighter in water.

24. Archimede’s Principle Archimede’s Principle states that the weight of the fluid that is displaced by an object is equal to the buoyant force of the object.

25. Why do objects float other than buoyancy? Density = Mass Volume MassMass = the amount of material a substance has. VolumeVolume = the amount of space an object occupies.

26. Density is a Characteristic Trait Density is like a fingerprint for a substance. Every known substance will have a specific density. Water = 1 g/ml or 1 g/cm 3 Aluminum = 2.7 g/ml (sinks in water) Wood = 0.5 g/ml (floats in water) Ice = 0.92 g/ml (floats in water) Lead = 11.3 g/cm 3 (sinks in water)