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L2 Forces, Mass, Acceleration, Pressure, Review of Exponents. Frictionless motion Demo. 5. NEWTON’S FIRST LAW OF MOTION. Newton finished the overthrow of Aristotelian ideas. Law 1 (Law of Inertia)
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L2 Forces, Mass, Acceleration, Pressure, Review of Exponents
5. NEWTON’S FIRST LAW OF MOTION Newton finished the overthrow of Aristotelian ideas. Law 1 (Law of Inertia) Every object continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it. “If you leave an object alone, it has constant velocity.”
Newton's concept of motion said that the natural state of an object was (a) constant velocity (b) constant acceleration (c) constant net force
We call the change in velocity per unit time the accelerationa= Δv/ ΔtThe Δv can be in magnitude and/or direction
The combination of forces that act on an object is the net force. (Only the net force is shown in the figures on this slide.) m m m This symbol means proportional to FORCE CAUSES ACCELERATION F a F a F a The acceleration of an object is directly proportional to the net force.
5. NEWTON’S SECOND LAW OF MOTION • The force in each of these equations represents the vector sum of all of the forces acting on the object of mass m. • Units of force - N and lb or
slug) A slug weighs Every object possesses inertia (mass). Inertia is the sluggishness of an object to changes in its state of motion. Mass - a measure of the inertia of an object (Units - kg and 3. MASS AND WEIGHT 32 lb. • Inertia deals with how hard it is to start and stop an object.
m1 m2 r Newton's Law of Universal Gravitation
At earth’s surface,F = G mMe/Re2 orW = (Gme/Re2) m or W=(g)m orweight = mass x acceleration of gravityg = 9.8 m/s2
A 2 kg mass weighs:A) 2 NB) 19.6 NC) 32 ND) 105 NE) Not enough information given
2 Concepts of Mass: Equivalence of gravitational mass and Inertial massTheory of General relativity
Pressure=Force/contact areaOn left, the pressure on the bottom block, i.e. the weight of the top block/contact area, is lower than the pressure on the bottom block on the right.
1000 = 10 x 10 x 10 = 103 100 = 10 x 10 = 102 10 = 101 1 = 100 0.1 = 1/10 = 10-1 0.01 = 1/100 = 10-2 0.001 = 1/1000 = 10-3