DO NOW If I need to be at an appointment at 2:00 and I have to travel 10 miles. Will I make it if I walk at a speed of 5 miles per hour and it is now 1:00? T= d/s = 10/5 =2 hours NO, you’re late

Motion OBJECTIVE(S): Define Motion Calculate speed, velocity, momentum, and acceleration of an object Distinguish between speed and acceleration

Motion Motion occurs when an object changes its position over a period of time Are you moving right now? YES! The Earth’s orbit around the sun is 600 million miles, We are traveling at 66,000 mi/hr through space! We are rotating at a rate of approximately 700-900 mi/hr!

It’s about relativity! Motion can only be detected when one object can be compared with another We don’t feel like we are moving because we are moving with the Earth. However, in the car we feel like we are moving fast because of the stationary objects along the side of the road

s= d/t Speed The rate of change of motion Average speed = distance/time The units are therefore m/s s= d/t

Practice Questions: 40.0 km/hr 333.3 km/hr 75.0 mi. 27.3 hr A car travels 120 km in 3 hours. What is its speed? A train travels 500 km in 1.5 hours. What is its speed? If a car was moving at 25 mi/hr and it took you 3 hours to get to your destination, then how far did you travel? You are planning a trip. Your destination is 1,500 miles away. You plan to drive 55 miles per hour. How long will it take to arrive at your destination? 40.0 km/hr 333.3 km/hr 75.0 mi. 27.3 hr

Graphing Speed: Distance vs. Time Graphs Denver Phoenix

Graphing Speed: Distance vs. Time Graphs Speed = Slope = Rise/Run Rise

Different Slopes Slope = Rise/Run = 0 km/1 hr = 0 km/hr Rise = 2 km Run = 1 hr Run = 1 hr Rise = 1 km Slope = Rise/Run = 2 km/1 hr = 2 km/hr Run = 1 hr Slope = Rise/Run = 1 km/1 hr = 1 km/hr

Do now: Define Speed and give the formula. Describe how the slope of a distance over time graph relates to speed.

Velocity What is the difference between speed and velocity? Velocity includes DIRECTION! Do speed and velocity have to be the same? NO!

Displacement Measures the change in position of an object Only the starting and ending points are used to find displacement Direction of motion is important A B

Velocity The rate of change of displacement Includes both speed and direction Average velocity = displacement over time Average speed is not always the same as average velocity

Velocity Equation V=d/t remember…. d= DISPLACEMENT

Do Now Pass your homework to the end of the row Calculate the average speed of a car that drive 30 km west, makes a U Turn, and drives 70 km east in a total time of 27 min. Calculate that car’s average velocity

Acceleration Rate of change of velocity How is velocity changing over time A = (Vf- Vi) t Change in velocity Over time. UNITS: Distance/time/time m/s2 mi/h/s km/h/s

Important Facts Acceleration is positive if velocity is increasing Acceleration is negative if velocity is decreasing Acceleration is zero if there is no change in velocity

Practice A roller coaster car rapidly picks up speed as it rolls down a slope. As it starts down the slope, its speed is 4 m/s. But 3 seconds later, at the bottom of the slope, its speed is 22 m/s. What is its average acceleration?

Practice A car advertisement states that a certain car can accelerate from rest to 70 km/h in 7 seconds. Find the car’s average acceleration.

Do Now At Six Flags, Kingda Ka can travel from 0 mph to128 mph in 3 seconds. Calculate the acceleration

Do Now Iron Man is flying forward through the air at a velocity of 87 km/hr. He sees Hulk throw a truck at him and decelerates at a rate of -25 km/hr/s for 4 seconds. What is his new velocity? What direction is he flying now?

Speed vs. Acceleration Which car is accelerating? How can you tell from the animation? http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/kinema/stl.html

Greatest Acceleration Which car(s) are accelerating? Which car(s) are moving at a constant speed? Match the cars with the lines on the graph. GREEN AND BLUE RED RED = Line B GREEN = Line C BLUE = Line A No Acceleration Accelerating Greatest Acceleration Constant Speed http://www.glenbrook.k12.il.us/gbssci/phys/mmedia/kinema/acceln.html

Graphing Acceleration Can use 2 kinds of graphs Velocity vs. time Distance vs. time

Graphing Acceleration: Speed vs. Time Graphs Speed is increasing with time = accelerating Line is straight = acceleration is constant

Graphing Acceleration: Speed vs. Time Graphs Rise = 4 m/s Run = 2 s In Speed vs. Time graphs: Acceleration = Rise/Run = 4 m/s ÷ 2 s = 2 m/s2

Graphing Acceleration: Distance vs. Time Graphs On Distance vs. Time graphs a curved line means the object is accelerating. Curved line also means your speed is increasing. Remember slope = speed.

Question Run = 3 s Rise = -6 m/s Above is a graph showing the speed of a car over time. 1) How is the speed of the car changing (speeding up, Slowing down, or staying the same)? 2) What is this car’s acceleration? The car is slowing down Acceleration = rise/run = -6m/s ÷3s = -2 m/s2

curved line = accelerating, flat line = constant speed Question: The black and red lines represent a objects that are accelerating. Black is going a greater distance each second, so it must be speeding up. Red is going less each second, so must be slowing down Remember: in distance vs. time graphs: curved line = accelerating, flat line = constant speed Which line represents an object that is accelerating?

Do Now Using the above graph, calculate the average velocity for the runner from 0 to 3 seconds. Calculate the average velocity from 3 to 5 seconds

Do Now You have 5 min after the second bell to revise your lab, it will be collected immediately after that time. Any copying will result in a 0

Inertia and Momentum As we already know, mass is the amount of matter an object possesses Inertia is the measure of an object’s tendency to remain at rest or stay in constant motion An object’s inertia is equal to its mass Momentum is the quantity of motion for an object

Momentum Thanks to Sir Isacc Newton, we can describe momentum as the product of mass and velocity Momentum = mass x velocity p = mv where p is the symbol for momentum Unit = kg·m/s Momentum is additive

Examples +3 kg m/s -2 kg m/s p = +1 kg m/s +3kg m/s -3kg m/s

Practice Questions: 280.0 g*m/s Object #1 An object has a mass of 20g. It is moving at 14 m/s. What is its momentum? 2. Two objects are moving at the same speed. #1 has a mass of 25 g, while #2 has a mass of 15 g. Which will have more momentum? 280.0 g*m/s Object #1

Law of Conservation of Momentum For a collision occurring between object 1 and object 2, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision. That is, the momentum lost by object 1 is equal to the momentum gained by object 2.

Conservation of Momentum This law states that the momentum of a system of objects will not change unless an outside force acts on the group. 0 kg m/s 0.2 kg m/s Before Collision Ptotal= 0.2 kg m/s 0.15 kg m/s 0.05 kg m/s After Collision Ptotal= 0.2 kg m/s

A bowling ball will exert a greater force because it has more mass! Momentum Momentum = mass x velocity Example: A ping pong ball and a bowling ball are rolling at the same velocity. Which will exert a greater force if it hits you in the foot? A bowling ball will exert a greater force because it has more mass!

Practice A baseball player holds a bat loosely and bunts a ball. Express your understanding of momentum conservation by filling in the tables below. http://www.physicsclassroom.com/Class/momentum/u4l2b.cfm