Definitions What is the difference between a scalar

Definitions �What is the difference between a scalar and a vector quantity? You may be able to find this in your text. Keystones: 3. 2. B

Students will be able to: �Differentiate Speed and Velocity �Describe the problems with determining instantaneous velocity Keystones: 3. 2. B

Mechanics: Keystones: 3. 2. B

Kinematics: Keystones: 3. 2. B

Dynamics: Keystones: 3. 2. B

Frame of Reference: Keystones: 3. 2. B

Vectors vs. Scalars: �A Scalar quantity is fully described as magnitude only. For example, mass is measured in grams and has no direction. We would not say something has a mass of 20 grams North. �A Vector quantity is fully described with both magnitude and direction. We could say that someone pushes at 22 Newtons to the left. Keystones: 3. 2. B

distance vs. Displacement Keystones: 3. 2. B

Displacement vs. distance: �Displacement is a vector quantity. It describes the straight line distance from a starting position to a finish position. This will include a distance. For example, Kim could walk 4 miles north. �Distance is a scalar quantity. If Kim walks along a curved path, distance is measured along the path. There is no direction associated with it. Keystones: 3. 2. B

Velocity vs. Speed: �Velocity is a vector quantity. It describes how fast and what direction. An airplane pilot wants to know wind velocity because both how fast and what direction the wind is moving are important. �Speed is a scalar quantity. If you receive a speeding ticket, the officer is not interested in the direction that you were travelling. He only cares how fast. Keystones: 3. 2. B

Instantaneous Velocity Keystones: 3. 2. B

To Sum it up… Scalar vs. Vector distance vs. Displacement speed vs. Velocity Average velocity vs. Instantaneous Velocity Keystones: 3. 2. B

The Visit I drive to visit a friend in Jim Thorpe which is 3 miles north of Lehighton. But because of construction, I drove 9 miles to get there and the trip took me 12 minutes. What was my speed? My Velocity? Keystones: 3. 2. B

Home for the Holidays You are driving home from school steadily at 65 mph for 130 miles. It then begins to rain and you slow to 55 mph. You arrive home after driving 3 hours and 20 minutes. How far is your hometown from school? What was your average speed? Keystones: 3. 2. B

A bowling ball travelling with a constant speed hits the pins at the end of a bowling lane 16. 5 m long. The bowler hears the sound of the ball hitting the pins 2. 50 s after the ball is released from his hands. What is the speed of the ball? The speed of sound in air is 340 m/s. Keystones: 3. 2. B

The Pitch A batter hits a baseball directly back toward the pitcher. The pitcher catches the ball exactly 1. 15 seconds after the ball left his hand. He pitched the ball 55 mph and the mound to home plate distance is 60 feet. How fast was the ball moving after the leaving the bat? Keystones: 3. 2. B

For you to do: You should be able to do the problems from sections 2 -1 through 2 -3. Keystones: 3. 2. B