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## Bell Ringers

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**Bell RingerAug 14, 2012**• Grab an article from the box and read it. Don’t get lost in the unusual names or words. Simply highlight/underline them and move on. Then use the back to analyze the story. *Remember, I expect you silent during the bell ringer.**Bell RingerAug 15, 2012**• Grab a fishboning explanation and guide from the “box”. Use the article from yesterday(fire in the lab) and use the fishboning method to: • Write the main idea • Support your idea • Give take away message *Remember, I expect you silent during the bell ringer.**Bell RingerAug 16, 2012Questions for the Author**• Grab the reading strategy from the “box”. Read it and do it using the “Fire in the lab” story from Tuesday. *Remember, I expect you silent during the bell ringer.**Bell RingerAug 17, 2012A safe lab culture article**• Grab the article from the “box”. Read it. *Remember, I expect you silent during the bell ringer.**Bell RingerAug 20/21, 2012**• If it takes one second for light to travel from the moon to the earth and 8 minutes for light to travel from the sun to the earth, how far away are the moon and sun?**Bell RingerAug 22/23, 2012**• Write as many scalar quantities as you can think of. • Write as many vector quantities as you can think of. • Find the component form of the following vector.**Bell RingerAug 24/27, 2012**• We are going to the library. • You will need to create: • Gmail account • Edmodo account • Dropbox account**Bell RingerAug 30/31**• What is gravity? • Where does it come from? • What kinds of things have gravity? • I have two masses. One is a basketball. The other is a 5lb bag of potatoes. If I hold them at the same height and drop them at the same time, which one hits the ground first? • Do they have a constant velocity? • Do they have the same gravitational force acting on them?**Bell Ringer Sept 4/5**• Consider the graph at the right. The object whose motion is represented by this graph is ... (include all that are true): • moving in the positive direction. • moving with a constant velocity. • moving with a negative velocity. • slowing down. • changing directions. • speeding up. • moving with a positive acceleration. • moving with a constant acceleration.**Bell Ringer Sept 6/7**• A car (A) moves to the left with speed 40km/h (with respect to the road). Another car (B) moves to the right with speed 60km/h(also with respect to the road). Find the relative velocity of B with respect to A. • After 5s a car is moving 20km/h. It uniformly accelerates to 60km/h in 15s. If the car were to continue to accelerate at the same rate how fast would it be going after a total time of 1 min. Use a graph to estimate the value.**An ice cube melts at a constant rate. For every increases of**3degress in the room temperature ice will melt 6ml of water. Use a graph to determine the how much ice has melted if the room temperature has increased a total of 13degress.**A car (A) moves to the left with speed 40km/h (with respect**to the road). Another car (B) moves to the right with speed 60km/h(also with respect to the road). Find the relative velocity of B with respect to A.**Sept. 17/18**• What is a force? http://www.youtube.com/watch?v=GmlMV7bA0TM&feature=relmfu • Why does the Earth spin? Explain. http://www.youtube.com/watch?v=TQxeutcYP6I&feature=edu&list=PL772556F1EFC4D01C • If you stopped the Earth from spinning, would it stay stopped or not? Explain.**Sept 19**• What are Newton’s Three Laws? • What is wrong with Derrick’s Laws**Sept. 25/26**• What is momentum? Example. • What is impulse? Example. • What is the Law of Conservation of Momentum? Example**Sept 27/28**A motorboat traveling 4 m/s, East encounters a current traveling 3.0 m/s, North. • What is the resultant velocity of the motorboat? • If the width of the river is 80 meters wide, then how much time does it take the boat to travel shore to shore? • What distance downstream does the boat reach the opposite shore? http://www.physicsclassroom.com/class/vectors/u3l1f.cfm#soln (See examples 1 and 2 for explanations)**Oct 1/2**At a railway station, two trains slowly collide in order to “couple” (join together). If one train of mass 12000kg is moving at 0.75m/s and the other of mass 3000kg is stationary, calculate the velocity of the two as they move away.**Oct 3/4**• Ball A travelling with speed V in the direction shown makes a glancing collision with stationary ball B of the same mass. After the collision the balls move off with speeds Va and Vb in the directions show on board. Which one of the following is true? Explain. • A) Vacosα = Vbcosβ • B) Va sin α = Vbsingβ • C) V = Vacosα + Vbcosβ • D) V = Va + Vb**Answer: A**• Since momentum is a vector quantity, direction is also conserved i.e. momentum in the +x to –x direction = 0. Vacosα = Vbcosβ**Oct.5/8**Come in have a seat. Expected grades. We have a force quiz – 30min Start collision lab – 45min**Oct. 9/10**• Define weight • What is Newton’s 3rd Law • Use the given triangle to solve for “x” • Add the following vectors: • 4m/s @45deg • 9m/s @150dg**Oct. 11/12**• A 0.1kg ball moves at 5m/s bounces off a vertical wall without a change in its speed. If the collision with the wall lasted for .1s what force was exerted on the wall? • A ball of mass.25kg moves on a frctionless horizontal floor and hits a vertical wall with speed 5m/s. the ball rebounds with speed 4m/s. If the ball was in contact with the wall for .15s, find the average force that acted on the ball. • Bullets of mass .03kg are being fired from a gun with a speed of 300m/s at a rate of 20 bullets per second. What force is being exerted on the gun?**Oct 16/17**• A man of mass “m” stands on a cart of mass “M” that rests on a horizontal frictionless surface. If the man begins to walk with velocity “v” with respect to the cart, how will the cart move? • What happens when the man gets to the edge of the cart and stops walking?**Oct 22**• A stationary body(A) of mass 12kg is hit by a 4kg mass(B) moving at a velocity of 12m/s. Body A moves off at an angle of 60degree to the left of the original direction. Body B moves off at an angle of 30 degrees to the right of the original direction. • What are the speed of the two masses after the collision?