View
215
Download
0
Category
Preview:
Citation preview
The last days
• Today –Review N7-N10 test, begin review for the final
• Thursday – Open lab, Work on any unfinished lab or problems
• Friday – Review (energy problems using CPS.
• Monday – review• Tuesday – Open lab• Wednesday – 7:00 – 10:00 Final Exam -
All work and extra credit due.
N7-N10 test results
• 90 – 100 10 students
• 80 – 89 7 students
• 70 – 79 5 students
• 55 – 69 4 students
Overall average in the class
• 90 – 100 5 students
• 80 – 89 13 students
• 70 – 79 5 students
• 55 – 69 3 students
Students in this range have a very good possibility of receiving an “A” in the class
Most probable grade is a “B”
Most probable grade is “C”
The above estimates are based on past experience. Past experience has also shown that students can move from one of these groups to another.
Chapter N11
Oscillatory Motion
Hooke’s law
xkF sxSp ,
xdt
xd 22
2
)cos()( tAtx
The force an ideal spring exerts on an object at position x.
The second derivative of the position with respect to time. A differential equation.
A constant that tells how stiff the spring is.
m
ksThe solution to the differential equation. This gives the position of the object as a function of time. – The equation of motion.
The mass of the object attached to the spring.
Phase angle
Sinusoidal Waves
)cos(),( tAtxf
2
fAmplitude of the wave
Phase rate
ω = angular frequency = 2πf
f = frequency = number of waves per second
f = frequency
Period = T = 1/f = time between wave crests passing a given point.
Simple harmonic motion
Simple harmonic motion
Phase Angle
These two oscillations have the same frequency and period but differ by a phase angle of 50º.
50º
• A 1 kg weight hung on a spring causes the spring to stretch 30 cm. If the weight is hung on the spring, then pulled down 5 cm and released, what is the equation of motion of the weight?
• Step 1, find the spring constant.• F = -kx• F = 9.8 N, x = 0.3 m• k = F/x = 32.7 N/m
sec/72.51
/7.322 rad
kg
mn
m
kf
y = y0Cos(ωt) = 0.05 Cos(5.72t)
Problems for Friday
• N11B1, B2, B3, S1
The last days
• Today – chapter N11, our last new chapter
• Tomorrow – Ballistic pendulum lab
• Wed –begin review for the final
• Thursday – Open lab, Work on any unfinished lab or problems
• Friday – Review
• Monday – review
• Tuesday – Open lab
• Wednesday – Final Exam
The last days
• Today –Review N7-N10 test, begin review for the final
• Thursday – Open lab, Work on any unfinished lab or problems
• Friday – Review (energy problems using CPS.
• Monday – review• Tuesday – Open lab• Wednesday – 7:00 – 10:00 Final Exam -
All work and extra credit due.
Recommended