GravityQuestions•What is Newton’s law of gravity?•What does “gravitationally bound” mean?•What are the four fundamental forces?Quiz 1, Question 1Which particle is not made up of quarks?A)ProtonsB)NeutronsC)ElectronsQuiz 1, Question 2What are the phases of matter that occur (in order) as temperature is increased from hundreds of Kelvin to tens of thousands of Kelvin?A)Liquid, gas, plasma, solidB)Plasma, solid, liquid, gasC)Solid, liquid, plasma, gasD)Solid, liquid, gas, plasmaNewton’s First Law of MotionForces cause acceleration:F = maForce = mass x accelerationUnits: Newtons = kg x m/s2Where acceleration is the time rate of change of momentum (mass x velocity)t=0,v=0t=1s,v=10m/st=2 s,v=20 m/sExample: A dropped ballConcept Question: AccelerationWhich car(s) is (are) accelerating?A. Car AB. Car BC. Both cars A & BD. Neither cars A nor BCar A: Moving at a constant speed of 30 mphCar B: Slowing down from 30 mph to a stopMass versus WeightMass is a property of an objectWeight is a forceFig. 5.3Newton’s Law of GravityGravitational Force = G x mass(Earth) x mass(object) / separation2Fg= GmEarthmobject/r2where G is the gravitational constantConcept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Concept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Hint: Fobject= mobjectaobjectNewton’s 1stlaw A. The more massive objectB. The less massive objectC. They will hit the ground at the same timeConcept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Hint: Fobject= mobjectaobjectNewton’s 1stlaw Fgravity= mEarthmobject/r2Newton’s gravityA. The more massive objectB. The less massive objectC. They will hit the ground at the same timeConcept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Hint: Fobject= mobjectaobjectNewton’s 1stlaw Fgravity= GmEarthmobject/r2Newton’s gravitymobjectaobject=GmEarthmobject/r2Set the forces equalA. The more massive objectB. The less massive objectC. They will hit the ground at the same timeConcept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Hint: Fobject= mobjectaobjectNewton’s 1stlaw Fgravity= GmEarthmobject/r2Newton’s gravitymobjectaobject=GmEarthmobject/r2Set the forces equalmobjectaobject=GmEarthmobject/r2Cancel mobjectA. The more massive objectB. The less massive objectC. They will hit the ground at the same timeConcept Question: Newton’s First LawIf a heavy object and a light object are dropped simultaneously, which will hit the ground first?Hint: Fobject= mobjectaobjectNewton’s 1stlaw Fgravity= GmEarthmobject/r2Newton’s gravitymobjectaobject=GmEarthmobject/r2Set the forces equalmobjectaobject=GmEarthmobject/r2Cancel mobjectaobject= GmEarth/r2Acceleration of objectA. The more massive objectB. The less massive objectC. They will hit the ground at the same timeConcept Question: Newton’s First LawWhat keeps the Earth in orbit around the Sun?Hint: Fgravity= GmEarthmSun/r2A.The Sun’s gravityB.The Earth’s gravityC.Their mutual gravitational attractionConcept Question: Newton’s First LawProfessor Glenn weighs 160 pounds on Earth. How much would he weigh if he were transported to empty space far from any astronomical body?Hint: Fgravity= GmProf. Glenn0/r2A. 160 poundsB. NothingC. More than 160 poundsEscape VelocityFig. 5.4With enough energy, objects can escape the gravity of the Earth—they are then not gravitationally bound to the Earth.Bound and Unbound OrbitsFig. 5.13Orbits can be bound (elliptical) or unboundThe Four Fundamental Forces•Gravity—mutually attractive force between massesThe Four Fundamental Forces•Gravity—mutually attractive force between masses•Electromagnetic—electricity and magnetism; binds atoms togetherThe Four Fundamental Forces•Gravity—mutually attractive force between masses•Electromagnetic—electricity and magnetism; binds atoms together•Weak Nuclear—governs nuclear reactions•Strong Nuclear—governs nuclear