Students did the pulley lab and looney tunes lab.
Both labs are due on Tuesday, Dec 16.
Test on Thursday, Dec 18.
Friday, Dec 19 - Physics poems/songs
On Friday, I collected RA 6.3.
Friday, December 12, 2008
Wednesday, December 10, 2008
Wednesday, Dec 10, 2008 - Blocks 1 and 3
Handed back and went over RA 6.1, RA 6.2
Wrote energy balance for pushing on block with friction and solved for final velocity. Solved the equation using acceleration to get the same answer.
Showed technique of inserting the coefficient into the KE or PE terms to calculate the new KE or new PE. Very powerful and useful technique. (Ex. What happens to the stopping distance of a car if you double the speed and double the mass?
KE old = 1/2 * m*v^2
KE new = 1/2 (2m) * (2v)^2 = 8 * 1/2 * m * v^2
Brought out swinging ball device and showed that situations that still obey conservation of momentum do not happen because they do not conserve energy.
Went over several energy balance equation situations.
Two balls coming together and stopping in inelastic collision. (Used steel balls to show energy is converted into heat that burns a hole through the paper.)
Roller Coaster Lab.
Car going up hill with friction.
Dropping a ball with no air resistance. How fast?
Looney Tunes Lab: At bottom, at half-way point, at 3/4 point down
Handed out RA 6.3 (due Friday)
Handed out CD 6.1, CD 6.2 due for last time next Wednesday.
Test on energy on Thursday of next week.
Friday: Physics poems and songs. Write an original poem or song and present it to the class.
Wrote energy balance for pushing on block with friction and solved for final velocity. Solved the equation using acceleration to get the same answer.
Showed technique of inserting the coefficient into the KE or PE terms to calculate the new KE or new PE. Very powerful and useful technique. (Ex. What happens to the stopping distance of a car if you double the speed and double the mass?
KE old = 1/2 * m*v^2
KE new = 1/2 (2m) * (2v)^2 = 8 * 1/2 * m * v^2
Brought out swinging ball device and showed that situations that still obey conservation of momentum do not happen because they do not conserve energy.
Went over several energy balance equation situations.
Two balls coming together and stopping in inelastic collision. (Used steel balls to show energy is converted into heat that burns a hole through the paper.)
Roller Coaster Lab.
Car going up hill with friction.
Dropping a ball with no air resistance. How fast?
Looney Tunes Lab: At bottom, at half-way point, at 3/4 point down
Handed out RA 6.3 (due Friday)
Handed out CD 6.1, CD 6.2 due for last time next Wednesday.
Test on energy on Thursday of next week.
Friday: Physics poems and songs. Write an original poem or song and present it to the class.
Tuesday, Dec 9, 2008 - Blocks 1 and 3
Collected RA 6.2
Talked about energy balance equations. Introduced Roller Coaster Lab.
Students did Roller Coaster Lab.
Write-up due on Thursday.
Talked about energy balance equations. Introduced Roller Coaster Lab.
Students did Roller Coaster Lab.
Write-up due on Thursday.
Monday, December 8, 2008
Monday, Dec 8, 2008 - Blocks 1 and 3
Collected RA 6.1
Handed back and went over Momentum Test
Collected tests.
Started energy
Walking on beach you find a magic lamp of physics.
Feynman's Block example
Places energy can hide - for this unit, GPE = m g h, KE = 1/2 m v^2, Elastic PE = 1/2 k x^2, work = F * d where F is the component of force in the direction of motion.
Showed that if the Earth went around the Sun in a circular orbit, the Sun would not do work on the Earth. If the orbit is elliptical, when moving towards the Sun, there is a component of force along the direction of motion so the Sun does work on the Earth and the Earth speeds up. When moving away, there is a component of force opposite the direction of motion so the Earth slows down.
Showed again the work done in pulling a block if the force is parallel to the surface and if the force is at an angle. For friction, the force is opposite the direction of motion so the friction force takes away energy in the form of heat.
Introduced Energy Balance Equation.
Did example of lifting a 10 kg mass. First at 120 N for 2 seconds, then at 100 N for 4 seconds and then at 60 N for 1 sec to slow it down. Drew force vs time graph. Showed applied force, weight, and net force. Since net impulse is zero, there is no change in momentum and the block comes to rest. Calculated the work done and showed that it was equal to the change in gravitational potential energy.
Main idea: If you lift an object, the work you do is equal to the increase in gravitational potential energy.
Handed out RA 6.2 and allowed students to work on it for tomorrow.
Handed back and went over Momentum Test
Collected tests.
Started energy
Walking on beach you find a magic lamp of physics.
Feynman's Block example
Places energy can hide - for this unit, GPE = m g h, KE = 1/2 m v^2, Elastic PE = 1/2 k x^2, work = F * d where F is the component of force in the direction of motion.
Showed that if the Earth went around the Sun in a circular orbit, the Sun would not do work on the Earth. If the orbit is elliptical, when moving towards the Sun, there is a component of force along the direction of motion so the Sun does work on the Earth and the Earth speeds up. When moving away, there is a component of force opposite the direction of motion so the Earth slows down.
Showed again the work done in pulling a block if the force is parallel to the surface and if the force is at an angle. For friction, the force is opposite the direction of motion so the friction force takes away energy in the form of heat.
Introduced Energy Balance Equation.
Did example of lifting a 10 kg mass. First at 120 N for 2 seconds, then at 100 N for 4 seconds and then at 60 N for 1 sec to slow it down. Drew force vs time graph. Showed applied force, weight, and net force. Since net impulse is zero, there is no change in momentum and the block comes to rest. Calculated the work done and showed that it was equal to the change in gravitational potential energy.
Main idea: If you lift an object, the work you do is equal to the increase in gravitational potential energy.
Handed out RA 6.2 and allowed students to work on it for tomorrow.
Friday, December 5, 2008
Friday, Dec 5, 2008 - Blocks 1 and 3
Impulse and Momentum test.
Students picked up RA 6.1 due Monday.
Students picked up RA 6.1 due Monday.
Thursday, December 4, 2008
Thursday, Dec 4, 2008 - Blocks 1 and 3
Block 1 - Handed back and went over momentum quiz
Gave students time to check end of chapter answers with members of other numbers.
Went over end of chapter exercises and problems
Went over problems from Momentum Problem worksheet.
Discussed format of test. No equations given. No really long problems.
Handed out optional worksheet on momentum
Test tomorrow
Gave students time to check end of chapter answers with members of other numbers.
Went over end of chapter exercises and problems
Went over problems from Momentum Problem worksheet.
Discussed format of test. No equations given. No really long problems.
Handed out optional worksheet on momentum
Test tomorrow
Wednesday, December 3, 2008
Wednesday, Dec 3, 2008 - Blocks 1 and 3
On RA 5.3 went over questions dealing with conservation of momentum in elastic and inelastic collisions. Momentum is conserved in BOTH types of collisions as long as there is NO net external force.
Went over definition of Conservation of Momentum. In the case of a falling object, it doesn't apply since there is an external force.
Did problem of inelastic collision in 2-D
Answered questions from homework problem set.
Gave momentum quiz
Showed part of Hewitt video on momentum dealing with boxing.
Students counted off by 4 and did assigned exercises and problems from end of chapter.
Tomorrow is the last day to hand in CD ch 5.
Went over definition of Conservation of Momentum. In the case of a falling object, it doesn't apply since there is an external force.
Did problem of inelastic collision in 2-D
Answered questions from homework problem set.
Gave momentum quiz
Showed part of Hewitt video on momentum dealing with boxing.
Students counted off by 4 and did assigned exercises and problems from end of chapter.
Tomorrow is the last day to hand in CD ch 5.
Tuesday, December 2, 2008
Tuesday, Dec 2, 2008 - Blocks 1 and 3
Handed back RA 5.3, Collisions Lab
Reviewed last class - elastic collisions
Elastic and inelastic collisions with multiple blocks.
In block 1 showed models of elastic collisions: slingshot effect, supernova
Demo of ballistic pendulum. Worked out problem to find initial speed of bullet.
Handed out problem sheets on momentum.
Quiz tomorrow on momentum.
Test on Friday, no equations given.
Reviewed last class - elastic collisions
Elastic and inelastic collisions with multiple blocks.
In block 1 showed models of elastic collisions: slingshot effect, supernova
Demo of ballistic pendulum. Worked out problem to find initial speed of bullet.
Handed out problem sheets on momentum.
Quiz tomorrow on momentum.
Test on Friday, no equations given.
Wednesday, Nov 26, 2008 Blocks 1 and 3
Handed back RA 5.2, Inelastic Collision worksheet
Collected RA 5.3
Reviewed collisions.
Collisions Lab
Bowling ball and golf ball competition.
In block 3 also showed models of elastic collisions - slingshot effect, supernova
Collected RA 5.3
Reviewed collisions.
Collisions Lab
Bowling ball and golf ball competition.
In block 3 also showed models of elastic collisions - slingshot effect, supernova
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