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Newton’s Second Law
• http://www.classzone.com/books/ml_science
_share/vis_sim/mfm05_pg50_newton/mfm05
_pg50_newton.html
• What conclusions can you draw about force,
mass, and acceleration from this simulation?
Newton’s Second Law
If you increase the mass…
• More force required to produce the same
acceleration
• OR the same force will produce less
acceleration
0.2 kg
3,500 kg
To increase the acceleration…
• Apply more force to the same mass
• OR decrease the mass
What if I increase the force?
• The same mass will accelerate faster
• An object with more mass will accelerate the
same
Units, units, units!
• Force = mass x acceleration
– Force measured in newtons (N)
– Mass measured in kilograms (kg)
– Acceleration measured in m/s2
• What are m/s2?
– Acceleration = change in velocity over time
Velocity
Time
=
m/s
s
“meters per second per second”
Let’s go back to the shopping carts…
• http://www.classzone.com/books/ml_science
_share/vis_sim/mfm05_pg50_newton/mfm05
_pg50_newton.html
• Does this equation seem to apply?
One more note…
• Forces in Newton’s 2nd law must be external
to the object on which they are acting!!!
Let’s practice!
• Find the mass of an object that accelerates 5
m/s2 when pushed with a force of 25 N
• Find the acceleration of an object with a mass
of 2 kg that is pushed with a force of 6 N
• Find the acceleration of an object with a mass
of 2 kg that is pushed with a force of 6 N
How is this related to Newton’s 1st
law?
• The more mass an object has, the more inertia
that object has, so you need more force to
change the object’s motion
Acceleration due to gravity
• On earth, this is a constant (g)
• g = 9.8 m/s2
Your turn!
• Complete the remaining problems on the
Newton’s 2nd Law handout
Exit ticket
• How much force would you need to apply to a
200 kg cart to accelerate the cart 5 m/s2?
Show your work and include units!
What factors must come together to
produce change?