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Forces and Motion. G ravity. Objects of different masses fall at the same rate. Galileo work Acceleration depends on force and mass. Change in velocity equation. Δ v = g X time The change in velocity ( Δ ) is the difference between the final velocity and the starting velocity. .
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Gravity • Objects of different masses fall at the same rate. • Galileo work • Acceleration depends on force and mass
Change in velocity equation • Δ v = g X time • The change in velocity ( Δ ) is the difference between the final velocity and the starting velocity.
Formulas for Velocity of falling objects • t = Δv/g or • Δ V = g X t or • . g = Δv / t
3 effects of Air resistance on a falling object • 1. Force of gravity= 9.8 m/s2 • 2. Force of air resistance= is the force pushing up on an apple • 3. Net force= Fg -Far
Falling objects • Leaf or Acorn
Free Fall • Facts about Free fall • A. No Air resistance • B. Only happens when you have gravity and no other force • C. Free fall can occur only when there is no air • D. Happens in space and in a vacuum • E. Orbiting objects are in free fall
Orbits • Need a forward motion • Need a gravity force • Both are needed to keep an object in orbit
Centripetal force • Is an unbalanced force that causes objects to move in a circular path • Usually this force is gravity
Projectile motion • Is the curved path an object follows when it is thrown or propelled near the surface of the earth. • It has two components a horizontal and a vertical motion which are independent of each other
Projectile Motion examples • 1. A frog leaping • 2. Water being sprayed by a sprinkler • 3. A swimmer diving into water • 4. Balls being juggled • 5. An arrow shot by an archer
Newton’s Laws of Motion • First Law of Motion = An object at rest remains at rest and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.
Newton’s Laws of Motion • Newton’s second law of motion- The acceleration of an object depends on the mass of the object and the amount of force applied.
Newton’s Laws of Motion • Newton’s third law of motion= Whenever one object exerts a force on a second object the second object exerts an equal and opposite force on the first.
Friction • An unbalanced force affects Newton’s first law of motion. This unbalanced force is friction. • Because of friction the motions of objects changes
Inertia • Is the tendency of all objects to resist any change in motion. • Law of Inertia aka Newton’s first law of motion • Mass is a measure of Inertia
Newtons • Newton = N • N = kg * m /s2
Formulas for 2nd Law • F = m X a or • A = F/m or • M = F/a
3rd law • Force pairs do not act on the same object • All forces act in pairs • The effect of a reaction can be difficult to see
Momentum • Is a quantity defined as the product of the mass and velocity of an object • Momentum is known as p
Formulas for P • P = m X v or • . m = p/v or • . v = p/m
Law of conservation of Momentum • States that any time objects collide the total amount of momentum stays the same • This law is true for any collision if no other forces act on the colliding objects. • This law applies whether the objects stick together of bounce off each other after they collide.