Embed Size (px)
Citation preview
Physics 2215: Newton’s Second Law
Purpose
• Use numerical integration to determine whether a physical system involved in a collision obeys Newton’s Second Law.
Physics 2215: Newton’s Second Law
Newton’s Second Law
dt
pdF net
Net forceacting on object
vmp ,where
pddtF net
Physics 2215: Newton’s Second Law
Newton’s Second Law, in case you didn’t recognize it
dt
dmvam
dt
dmv
dt
vdm
dt
pdF net
amF net , if m = constant (dm/dt=0)
Physics 2215: Newton’s Second Law
Impulse
pddtF net
pppdtFI if
t
t
net 2
1
“Impulse” Change in momentum
Impulse = Change in Momentum
Physics 2215: Newton’s Second Law
The Basic Idea of this Lab
pdtFIt
t
net 2
1
Numerically integrate themeasurements from theforce sensor during thecollision.
Measure momentumchange using the photogate
(vinitial before collision, and vfinal after collision)
Compare
Physics 2215: Newton’s Second Law
Setup for Elastic Collision
Air TrackGlider
eraser
Force Sensor
springphotogate
bumper with needle
flat bumper
A bit of clay as a counter-weight
Physics 2215: Newton’s Second Law
Elastic Collision – Measuring vinitial
Force SensorGlider
vinitial
Physics 2215: Newton’s Second Law
Elastic Collision – Measuring the force during the collision
Force SensorGlider
Physics 2215: Newton’s Second Law
Elastic Collision – Measuring vfinal(going through the photogate in the other direction)
Force Sensor
Glider
vfinal
Physics 2215: Newton’s Second Law
Setup for Inelastic Collision
Air TrackGlider
Modeling clay
Force Sensor
Modeling clayon hook (don’tuse spring)
photogate
Physics 2215: Newton’s Second Law
Inelastic Collision – Measuring vinitial
Force SensorGlider
vinitial
Physics 2215: Newton’s Second Law
Inelastic Collision – Measuring the force during the collision
Force SensorGlider
Physics 2215: Newton’s Second Law
Inelastic Collision : vfinal=0
Force SensorGlider
Physics 2215: Newton’s Second Law
The force-time diagram during the collision
time
force
Before collision:Force = 0 (if tared properly)
After collision:Force = 0 (if tared properly)
collision
Physics 2215: Newton’s Second Law
The force-time diagram during the collision
time
force
Discrete measurements incertain time intervals
collision
time force
get recorded alsoin a table in Capstone
Physics 2215: Newton’s Second Law
Numerical Integration using the Table Data
time (in s) Force (in N)
0.000.010.020.03………0.120.13…
0.000.000.010.02………0.030.010.00
before collision (f=0)
after collision (f=0)
Export these data to Excel.Integrate in Excel using the trapezoidal rule (see homework).
