Motion and Forces How we use physics in everyday life

Warm up 4/12/12 1.How can you figure out how fast something is going? 2.How would you define the word speed? 3. What factors would you consider to determine the speed of an object? For example: Size? Weight? Color?

Announcements If you received a letter informing your parents about your academic progress, you MUST have it signed and returned by Friday, April 13 th. You also need to make sure each of your teachers are signing a progress record for you at the end of each core class.

Intro to physics Physics is the study of matter and its motion through space and time, along with related concepts such as energy and force.mattermotionspace and timeenergyforce We already know that matter is anything that has mass and takes up space. During this unit, we will learn more about how matter moves using energy and different forces.

What is speed? Speed is the measure of how fast or how far something moves within a given amount of time. The higher the speed of an object, the faster that object changes its position. In other words, the higher the speed of an object the faster it moves!

How do we calculate speed? In order to find out the speed of an object, you must first determine its distance and time. Thus, speed is: Speed = Distance of an object Time traveled Or S= D T

Example 1 A wheel chair racer completes a 100 meter course in 20 seconds. What is his speed? Steps: 1.Ask yourself what do you know? Distance= 100 meters Time= 20 seconds 2. What do you want to know? Speed 3. s=d s= 100 s=5 meters per second or m/s t 20

Guided practice 1. A man runs 200 meters in 25 seconds. What is his speed? 2. If you travel 100 meters in 50 seconds, what is your speed? 3. Suppose a race is 50 meters, and it takes an athlete 15 seconds to run it. Is this enough information to calculate the runners speed?

What is velocity? Velocity is speed in a specific direction. For example, you are in a train travelling east at 75 miles per hour you are describing the trains velocity. In order to determine the velocity of an object, you need to know its speed and its direction.

Example 1

Vector Velocity is an example of a vector. A vector is defined as a quantity that has both size and direction. Speed is NOT a vector because it is a measure of how fast or slow an object moves, which is not a direction. Velocity has a size and direction and is therefore considered to be a vector.

Velocity vs. Speed Because velocity includes direction, its possible for two objects to have the same speed but different velocities.

Exit slip (quiz grade) complete on NBK paper 1.What is the formula for speed? 2.What two things do you need to know to calculate velocity? 3.Carlos lives 100 meters away from home. What is his average speed if he reaches his friends house in 50 seconds? (show your work) 4.True or false: Velocity is NOT considered a vector.

Warm Up 4/13/12 1.What is the formula for speed? 2.In order to determine the velocity of an object you must know what ___________ it is travelling. 3.A ___________ is defined as a quantity that has both size and direction. 4.Velocity is an example of a____________.

Announcements If you received a letter informing your parents about your academic progress, it is due today! Hand it in to me now if you have it You also need to make sure each of your teachers are signing a progress record for you at the end of each core class.

Review of exit slips 1.What is the formula for speed? S=d/t 2.What two things do you need to know to calculate velocity? Speed and direction of movement 3.Carlos lives 100 meters away from home. What is his average speed if he reaches his friends house in 50 seconds? (show your work) see board 4.True or false: Velocity is NOT considered a vector. False

Speed practice problems/Lab With a partner, you will be calculating speed. Once you and your partner are done, you will be allowed to complete the speed lab. Both sheets must be submitted to get full credit