Archimedes and Acceleration Archimedes Acceleration Pre-test/ Study Guide

Bell Work How does Archimedes principle apply to this picture? The metal cylinder originally was balanced with the metal piece on the other end. Now it is not Answer this thought in your notebooks and draw a sketch of the setup.

Bellwork Video and Discussion

Archimedes Four Square Using only your Prentice Hall Book – Draw this in your notebook and answer each Square. You will have 20 minutes to quietly work on this. Density 1.What is the formula for density? 2.How do you know if an object will float or sink? 3.Answer predicting question (in Figure 7 explanation on page 425) Buoyancy 1.What is the buoyant force? 2.Copy the Figure 10 on page 427 but DRAW THE FORCE ARROWS THE WAY WE LEARNED IN CLASS! Draw in the net force on each of the objects. 3.What force acts opposite the buoyant force? Archimedes’ Principle (Page 427-9) 1.What is “Archimedes’ Principle?” 2.Why did the two canisters in Figure 11 displace different amounts of water? (Displace means to move…) 3. Does the buoyant force change on a submarine as it rises or sinks? Practice 1.Copy figure 12 on page Why does the boat float when another object with a similar mass sinks? 3.How does this apply to the boat you made in the Penny Lab?

Acceleration!

Acceleration Let’s Review: What is Speed? Velocity? What is a Vector? Acceleration: RATE at which velocity changes Acceleration: RATE at which velocity changes Refers to INCREASING speed, DECREASING speed, or CHANGING direction. Refers to INCREASING speed, DECREASING speed, or CHANGING direction.

Is Acceleration a Vector? A softball accelerates when it is thrown, hit, or caught. What change in motion occurs in each example? Thrown- ball accelerates as it is thrown Hit- ball changes direction Caught- ball decelerates (negative acceleration) How can a car be accelerating if its speed is constant at 65 km/h?

The arrows are larger as the plane increases speed or accelerates…the arrows represent the vector quantity.

Calculating Acceleration Final Velocity - Initial Velocity Time V f - V i t Beginning Velocity Final Velocity Time a =

Example: As a roller coaster starts down a slope, its velocity is 4 m/s. But 3 seconds later, its velocity is 22 m/s in the same direction. What is its acceleration? Initial Velocity: 4 m/s Final Velocity: 22 m/s Time: 3 s Final Velocity – Initial Velocity/ Time 22 m/s – 4 m/s 3 s 18 m/s = 6 m/s/s or 6 m/s 2 18 m/s = 6 m/s/s or 6 m/s 2 3 s

Graphing Acceleration Speed vs. Time Graph Speed vs. Time Graph Upward means speed is increasing Upward means speed is increasing Line is straight means acceleration is constant A horizontal line (flat) would mean that the object is moving at a constant speed. A horizontal line (flat) would mean that the object is moving at a constant speed. Slope on a speed vs. time graph represents acceleration Slope on a speed vs. time graph represents acceleration

Distance vs. Time Graph Curved line means that the objects is accelerating (nonlinear). Curved line means that the objects is accelerating (nonlinear). During each second, the object traveled a greater distance than the second before. During each second, the object traveled a greater distance than the second before. Slope is speed and since slope is getting steeper and steeper, you can conclude that speed is also increasing…or that the object is accelerating. Slope is speed and since slope is getting steeper and steeper, you can conclude that speed is also increasing…or that the object is accelerating.

Let’s Practice

THE END!