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Intro to Forces and Motion. Ms. Graettinger Physical Science. What is a force?. Force is a push or pull on an object or by an object Force= mass x acceleration F=ma A force is that which changes or tends to change the state of rest or motion of a body. Newton’s 3 Laws. - PowerPoint PPT Presentation
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Intro to Forces and Motion
Ms. GraettingerPhysical Science
What is a force?
Force is a push or pull on an object or by an object
Force= mass x accelerationF=maA force is that which changes
or tends to change the state of rest or motion of a body.
Newton’s 3 Laws
1st : An object in motion stays in motion. An object at rest stays at rest--until an outside force acts upon it
2nd : F=ma3rd : For every action, there is an equal and opposite reaction
The Force Equation
F = ma
Force = mass x acceleration
Mass is in kgAcceleration is in m/s2
Force is in Newtons (N)
Force Equation Example
How much force is needed to accelerate a 70-kg rider and her 200-kg motorcycle at 4 m/s2?
F=maF=(70kg + 200kg) x (4 m/s2)
F=1080 N
Falling Objects
Any two objects falling from the same distance, released at the same time, will land at the same time
Why is this?
Acceleration due to Gravity
Falling objects accelerate at 9.8m/s2
Therefore,Weight=m x aW=m x 9.8m/s2
Air Resistance
The force air exerts on a moving object
If there is no force except for gravity, all objects will accelerate at a rate of 9.8 m/s2
Air Resistance
This force acts in the opposite direction to that of the objects motion
Air resistance pushes up while gravity pulls down
Air Resistance Example
Classwork:Everyone must calculate how much they really weigh in Newtons.
Conversion factor: 1kg=2.2 lb