Newton’s Laws Physical Science. 10/15 Obj: To review 1 st Law and begin 2 nd Law HW – Solve...
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Transcript of Newton’s Laws Physical Science. 10/15 Obj: To review 1 st Law and begin 2 nd Law HW – Solve...
Newton’s LawsPhysical Science
10/15 Obj: To review 1st Law and begin 2nd
LawHW – Solve Problems
Newton’s 1st LawState the law
and draw a picture or pictures demonstrating your
understanding of the law.
Sir Isaac Newton• 1643-1727
• Lived & worked in England
• Made major developments in physics, mathematics, religion, geography, chemistry & optical science
“If I have been able to see further, it was only because I stood on
the shoulders of giants.” —Sir Isaac Newton
Sir Newton was born the year that Galileo died
Newton’s Laws• Newton developed three laws that govern all
motion.
• They are named Newton’s 1st,2nd, & 3rd laws.
The Law of Inertia(Newton’s 1st Law)
• Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
The Law of Inertia(Newton’s 1st Law)
• to dislodge ketchup from the bottom of a ketchup bottle, the bottle is often turned upside down, thrust downward at a high speed and then abruptly halted.
• headrests are placed in cars to prevent whiplash injuries during rear-end collisions.
• while riding a skateboard (or wagon or bicycle), you fly forward off the board when hitting a curb, a rock or another object which abruptly halts the motion of the skateboard.
Inertia• Inertia is an object’s resistance to change
Inertia
• Inertia is an object’s resistance to change
http://www.lhup.edu/gp/PhysicsClub/demo_f00_eggdrop_2_movie.mov
A note about FORCE• A force is a push or pull upon an object
resulting from the object's interaction with another object.
• Force is measured in NEWTONS (N)
• 1 Newton = 1kg * 1m/s2
• FORCE is like velocity, it has a size AND direction and can be added the same way
• The NET FORCE or FNET = total of all forces
Newtons
Newton’s 2nd Law• Objects will only accelerate if they are acted
upon by an unbalanced force
• This is shown by:
Fnet = m * a
m
F
a
F=Force
M=mass
A=acceleration
a=f÷m
m=f÷a
Newton’s 2nd Law• How much net force is required to
accelerate a 1000 kg car at 5.00 m/s2?
F = m * aF = 1000kg * 5.00m/s2
F = 5000N
Newton’s 2nd Law• What is the mass of an object that is
accelerated to 20m/s2 by 100N?
m = F / am = 100N / 20m/s2
m = 5kg
Newton’s 2nd Law
Because this triple-beam balance scale measures
the mass (not the weight) of an object, it will read the same on any planet.
Newton’s 2nd Law• Is an unbalanced force acting on this car?
Newton’s 2nd Law – a version• MASS is how much there is of the object
• WEIGHT is the force required to support an object against the pull of gravity
Weight = mass * gravityw = m*g
Newton’s 2nd Law• How much does a 25kg child weigh?
w = m * gw = 25kg * 10m/s2
w = 250N
Newton’s Second Law
Newton’s 3rd Law
"For every action, there is an equal and opposite reaction."
Forces always come in pairs - equal and opposite action-reaction force pairs.
Newton’s 3rd Law
Newton’s 3rd Law
A cyclist traveled at 12 km/h for 5 hours. How far did he travel?