Motion Observing To observe an object in motion, you must use a referenced object. The one sitting still is considered to be the reference point. When an object changes position over time, compared to the reference point, the object is said to be in motion

Motion the rate at which an object moves two variables need to be considered a. distance b. time therefore: speed = distance time Speed

Motion Average speed is a measure of the distance traveled in a given period of time; it is sometimes referred to as the distance per time ratio. Suppose that during your trip to school, you traveled a distance of 5 miles and the trip lasted 0.2 hours (12 minutes). The average speed of your car could be determined as

Motion the speed of an object in a particular direction velocity always includes a reference point Velocity

Motion Resultant velocity this calculation is determined as follows a. if velocity is in the same direction e.g. b. if velocity is in opposite directions e.g.

Motion Acceleration is the rate at which velocity changes to apply a force to an object to make it slow-down, speed-up or change direction. To calculate acceleration: Acceleration = final velocity (m/s) – starting velocity (m/s) time it takes to change velocity (s) your answer will be in meter/second second

Observe the animation of the three cars below. Which car or cars (red, green, and/or blue) are undergoing an acceleration? Study each car individually in order to determine the answer. Now that you've answered the first question correctly, try this one: which car (red, green, or blue) experiences the greatest acceleration? As a final test of your understanding, consider the position-time graph at the right. Each one of the three lines on the position-time graph corresponds to the motion of one of the three cars. Match the appropriate line to the particular color of car.

Motion either a push or a pull; net force Force in combination Force in the same direction Force in different direction Unbalanced force produces a change in acceleration net force is greater than zero Balanced force produces no acceleration net force is zero Force

hills and valleys Motion force that opposes motion between two surfaces that are touching Greater the force, greater the friction Friction

Motion Gravity force of attraction between objects that is due to their masses note: all matter experiences gravity in other words (Gravity sucks; it never spews.)

Motion Weight a measure of the gravitational force exerted on an object note: weight and mass are different

Motion Gravity and Motion all objects fall to the ground at the same rate how? difference in force is canceled by the difference in mass What would hit first, elephant or feather?

Motion Accelerate at constant rate all objects accelerate toward the ground at the same rate the rate or velocity is 9.8 m/s s remember: we are not talking about distance

Motion Air resistance slows down acceleration air resistance continues to increase until it matches the downward force of gravity object then falls at a constant velocity called terminal velocity

Motion Another example of terminal velocity Remember, the increase in air resistance continues till it is even with gravity

Motion Free fall no air resistance can only occur in a vacuum the only force acting is gravity

Motion Orbiting created by forward and gravitational forces occurs when an object is circling around another object

Motion less than 8000 m/s equal to 8000 m/s greater than 8000 m/s

Motion Newton’s Laws of Motion Three laws that relate forces to the motion of objects First law aka. law of inertia An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Motion Second Law due to unbalanced force that the acceleration of an object is dependent upon two variables a. the net force acting upon the object and b. the mass of the object the net force – objects acceleration increases as the force increases e.g. shopping cart mass of the object – objects acceleration decreases as its mass increases a = F m

Motion Third Law that for every action (force) in nature, there is an equal and opposite reaction; force pairs in other words: if object A exerts a force on object B, then object B also exerts an equal force on object A note: we are only talking about forces

Motion Momentum property of a moving object that depends on the object’s mass and velocity in other words: more momentum an object has the harder it is to stop the object Conservation (constant) of momentum That is, the momentum lost by object 1 is equal to the momentum gained by object 2

Motion Energy the ability to do work remember, work is a transfer of energy so therefore work only occurs if the force and motion are in the same direction Work = F x d; force times distance since force is in Newtons (N) and distance is in meters the new label is J or Joules

Motion Energy of Motion called kinetic energy as long as an object is moving there is kinetic energy kinetic energy depends on mass and velocity creating work

Motion Energy of position called potential energy gravitational potential energy depends on weight and height tells us about stored energy that has the capacity to do work

Motion Mechanical energy kinetic energy + potential energy as the height decreases the PE also decreases as the speed increases so does the kinetic energy

Motion Types of energy

Motion Conservation of energy energy can be neither created nor destroyed total amount of energy in a closed system is always the same with conversion of energy you always get thermal energy what are the energies in the rollercoaster ride?

Motion Temperature temperature depends on the kinetic energy of the particles as a substance gets hotter, it’s particles moves faster

Motion Temperature conversion

Motion Heat transfer of energy between objects of different temperatures energy is transferred from higher temperatures to lower temperatures

Motion Types of energy transfer a. conduction – heat transfer by direct contact higher kinetic energy to lower kinetic energy b. convection – heat transfer by movement of liquid or gas c. radiation – heat transfer as electromagnetic waves