Forces in 1D
Forces in 1D. What is a FORCE ?. A push or pull Interaction between two objects Can cause a change in motion of the object Vector. Objects actually touch. Objects do not have to touch “Force field”. Gravity. Contact vs. Field Forces. Types of Forces. Free Body Diagrams.
Forces in 1D
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Presentation Transcript
What is a FORCE? • A push or pull • Interaction between two objects • Can cause a change in motion of the object • Vector
Objects actually touch • Objects do not have to • touch • “Force field” • Gravity Contact vs. Field Forces
Free Body Diagrams • Picture that diagrams ALL forces present • Direction AND magnitude are considered Fn Ff Fapp Fg
Balanced vs. Unbalanced Forces • Forces cancel out • Equal and opposite • Fnet = 0 • Constant speed = 0 acceleration • Forces do NOT cancel • Forces are not equal • Have a Fnet • Do have acceleration
490 N Fn Ff Fapp -300 N 300 N Fg -490 N
Newton’s Laws • 1st law • Inertia • An object in motion will stay in motion/an object at rest will stay at rest UNLESS acted upon by an outside force • 2nd law • Fnet = ma • The net force on an object is proportional to its mass and acceleration • Fnet = 0 • 0 acceleration • balanced forces • Fnet > 0 • has acceleration • unbalanced forces
Force due to Friction Static vs. Kinetic Objects in motion • Keeps an object from moving • Fapplied = Fstatic to start movement • The amount of friction depends on the SURFACES that • are in contact Ff = Fn • - coefficient of friction
Example The combined mass of a sled and its rider is 46.4 kg. The sled is pulled across a frozen lake so that the force of friction between the sled and the ice is very small. • A force of 150.0 N is applied to the sled and produces an acceleration of 3.00 m/s2. What is the magnitude of friction that resists the acceleration? • What is the coefficient of friction between the sled and ice?
Newton’s Laws • 3rd Law • For every action, there is an EQUAL and OPPOSITE reaction