Physics. The study of energy & matter and how they interact

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Oswald Powers
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1 Physics The study of energy & matter and how they interact

2 Forces a push or pull on an object. Drawn as a vector - have direction and strength Measured in. newtons 5 n

3 Net Force when in the same direction it is the sum of all forces acting on an object. when in opposite directions it is the difference of the forces Measured in. newtons 5 n 5 n 5n - 5n = 0 n (net force) no movement 5 n 5 n 10 n 5 n Result of all forces on object 5n + 5n = 10 n (net force) movement to right 10n - 5n = 5n (what way will it move?)

4 Bridge Example Draw & Answer Ms. Dorr puts water in a bucket hanging off your bridge. The bucket is pulled down by gravity with 285 n of force. The reaction force of the bridge is 285 n. What happens to the bridge and why? Ms. Dorr she then adds one cup of water to the bucket increasing the force of gravity on the bucket by 10 n. The reaction force stays the same. What happens to the bridge and why?

5 Balanced Force Force in one direction the force in the opposite direction Object does not move Net Force = 0 n equals

6 Unbalanced Force Force in one direction than the force in the opposite direction greater moves in the direction of Object the greater force Net Force > 0n

7 Newton s 1st Law also called inertia An object at rest will stay at rest and an object in motion will stay in motion (at the same speed & direction) unless an unbalanced force acts on it. objects keep doing what they are doing until acted on by an unbalanced force The greater the mass, the greater the inertia

8 Newton s 2nd Law Force = mass x acceleration the greater the mass - the greater the force the greater the acceleration (speed) - the greater the force The amount of force something has depends upon its mass and how fast it is going

9 Newton s 3rd Law For every force there is an equal and opposite force Ex: a book pushes on the table and the table pushes back on it. Action Reaction

10 Friction the force that one surface exerts on another when the 2 rub against each other Always opposite direction of movement movement friction

11 Energy the ability to do work or cause change to be able to push or pull an object - create force

12 Potential Energy energy that is stored in an object can be because of its position the higher the object the more the potential energy (gravity) also if you stretch or squish something Example: Yoyo near your hand Rubber band that is stretched rock at the top of a cliff

13 Kinetic Energy energy of motion The faster the object or the greater the mass, the more kinetic energy potential can be transformed into kinetic Example: Yoyo falling Rubber band released rock falling off cliff

14 Energy Changes Sometimes kinetic & potential energy can be changed back & forth into eachother. Potential energy can be changed to kinetic Example: Rock falls off cliff Rubber Band is released Kinetic energy can be changed to potential Example: A ball is thrown on the roof pendulum swings up

15 Pendulum an object that swings from one point one time that the object swings and then comes back to the same position is called a period

16 Pendulum Potential Potential kinetic 4 5

17 Conservation of Energy Energy is not created or destroyed It can be converted from one kind to another Example: Flashlight - electrical energy to light energy Waterwheel - energy of motion to mechanical energy

slb.com/en/scictr/lab/galileo/index.htm http://www.

18 Galileo On the Moon - acceleration from gravity does not change - is a constant 9.8 m/sec2 resource/phy03.sci.phys.mfw.galmoon/

19 Motion change in position or place an object is in motion when its distance from another object changes

20 Reference Point what you compare an object to when determining if it is in motion.

21 Speed distance traveled per ONE unit of time Distance/Time Units: miles/hr, meters/sec Example: A student walks 2 miles to school in 0.5 hour what is the speed? 2/0.5 = 4 miles/hour

22 Constant Speed speed does not change for entire time example: Average Speed speed does change during time calculate by total distance/total time example:

23 5 4 Distance (m) Time (sec)

24 Distance vs. Time Graphs RULE The steeper the slope - the greater the speed!!! Slope = Speed

25 Draw a sketch of a distance-time graph... with two lines, one traveling at a slow speed, one at a faster speed. Label them. fast Distance slow Time

26 Draw a sketch of a distance-time graph... that is traveling at constant speed distance

27 Draw a sketch of a distance-time graph... that is not traveling at constant speed distance

28 Draw a sketch of a distance-time graph... of an object that is standing still distance time

29 Velocity Distance traveled per unit of time in a specific direction Units: miles/hour in a certain direction Example: 4 miles/hour southwest

30 Acceleration rate of change in velocity. (speed & direction)

31 Draw a sketch of a distance-time graph... of an object that is accelerating distance time

A. true. 6. An object is in motion when

A. true. 6. An object is in motion when 1. The SI unit for speed is A. Miles per hour B. meters per second 5. Frictional forces are greatest when both surfaces are rough. A. true B. false 2. The combination of all of the forces acting on an