physics on the road-lesson 10
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Forces
Physics on the RoadLesson 10
Isaac Newton’s LawWe are learning
to…. understand that the
acceleration of something depends upon it’s mass and the resultant forces acting on it.
recall and use the formula
Force = mass x acceleration (F=ma) Investigate the effects
of an unbalanced force using equations of motion.
Linking force and motion
Philosophers and scientists have been linking force to motion since 300 B.C.Not always well.
Forces keep things moving
Aristotle 325 BC
Forces cause motion but are not needed to
keep them moving
Galileo 1630
Close but no cigar
Newton 1675
Newton’s Laws First Law
If there is no resultant force an object will remain at rest or if moving continue moving at a constant speed.
Second LawIf there is a resultant force an acceleration proportional to the force will occur.
InertiaReluctance to change speed.Depends upon mass.
Force = mass x acceleration
(N) (kg) (m/s2)
m x a
F
Calculation QuestionsF UNCAU
Q1. What force is needed to give the 800 kg drag car an acceleration of 5 m/s2?
Q2. A rocket has a mass of 5000 kg. It’s engines provides a force of 200 000 N. What is the rocket’s acceleration?
Wacky Race
Boeing 747Mass = 200 000 kgEngine Force = 500 000 N
Porsche 911Mass = 1500 kgEngine Force = 9000 N
Honda CBRMass = 200 kgEngine Force = 1600 N
m x a
F
a = F / m = 500000 / 200000 = 2.5 m/s2
a = F / m = 9000 / 1500 = 6 m/s2
a = F / m = 1600 / 200 = 8 m/s2
Forces cause acceleration
What can we vary?What will that vary?How should we measure this?
Experiment design
Can we measure the acceleration? Are there other measurements we
can make to calculate the acceleration?
Design your experiment and data table carefully.
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