Turn to a partner and discuss Newton s Law of Universal Gravitation ass? Mass is the aount of atter in an object.! a easure of the inertia of an object.! easured in units of kilogras.! constant everywhere.!! No atter where I take you, your ass doesn t change.! Turn to a new partner and discuss inertia?
Inertia is One ore partner question a property of atter. a easure of an object s resistance to changes in its otion.! resistance to changes in speed and/or direction. directly proportional to an object s ass.! ore assive objects have ore inertia. weight? Weight is Weight Calculations another nae for the force of gravity which the planet exerts on an object near its surface.! We typically speak of our weight on Earth so we are talking about the force of gravity that the Earth exerts on us. a force. dependant on BOTH your ass and the planet which you are on or near. Weight = Mass * (Gravitational ield Strength) Gravitational ield Strength depends on the planet and the exact location. On Earth, gravitational field strength = g= 9.8N/kg.! In other words, the earth exerts 9.8N of force on you for every 1 kg of ass. On Earth,! Weight (in Newtons) = Mass (in kilogras) * 9.8N/kg
English versus Metric Units Metric Units English Units Mass Kilogras Slugs Weight Newtons Pounds (lbs) Note: 9.8 Newtons = 2.2 lbs! WMG! Og! This one equation is not included on your MCAS forula sheet! W = g W: weight (N) : ass (kg) g: gravitational field strength (N/kg or /s/s) g = 10 /s/s on earth Question #1 Question #2 Deterine the weight (in Newtons) of a 64 kg object on planet Earth.! g = 10 N/kg Weight =? = 64 kg Deterine the ass (in kilogras) of an object which weighs 200 N on planet earth.! Weight = g Weight = 64 kg 10 N/kg Weight = 640 N
True and alse More True and alse T 1. More assive objects have ore inertia than less assive objects.! 2. If the forces acting upon an object are balanced, then it ust be at rest.! 3. On Earth, the force of gravity acting upon an object is 9.8 ties the weight of the object.! 4. Inertia is a force which acts upon objects at rest.! 5. A feather and an elephant will have the sae weight within a vacuu.! 6. If you stand on a bathroo scale and bounce, the scale reading changes. This eans that you weigh differently ( ore or less) than if you were to standing at rest.! More True and alse Turn to a partner and discuss: 7. More assive objects have the sae inertia as less assive objects; yet ore assive objects will weigh ore.! 8. The weight of an object can be expressed in units of kilogras or gras.! the force of gravity? 9. Weight and ass are the sae thing; it's just that they have different values on different planets.!
The orce of Gravity is the force of attraction which any two objects that have ass exert on each other.! only noticeable when at least one of the objects has a very, very large ass.!! When dealing with situations on Earth, we are only interested in the gravitational force that Earth exerts on objects.! Newton s Law of Universal Gravitation ANY two objects which have ass exert an attractive force on each other which is directly proportional to the product of the asses and inversely proportional to the square of the distance between the. g where G = gravitational constant 1 is the ass of one object. 2 is the ass of the second object. d is the center to center distance between the objects. Note : g G Newton s Law of Universal Gravitation Three Things for you to know:! bigger if the objects have ore ass.! saller if the objects are farther apart.! universal. It applies to ANY two objects which have ass. Why is gravity so special? It is universal. It does not require contact. It is poorly understood. Note: When people say gravity they typically ean the force of gravity. Reeber that we are talking about a force.
T True and alse 1. You and your lab partner will experience a force of gravitational attraction when standing next to each other.! 2. There is no gravity on the oon.! Practice Probles Situation A) 2 objects, each with ass of are distance d apart. What would happen to g if the ass of one object doubles? g d 2 Practice Probles Practice Probles Situation B) 2 objects, each with ass of are distance d apart. What would happen to g if the ass of both objects doubles? Situation C) 2 objects, each with ass of are distance d apart. What would happen to g if the distance between both objects doubles? 2 d 2 g 2d g
Practice Probles Situation D) 2 objects, each with ass of are distance d apart. What would happen to g if the ass of one object triples and the distance between both objects doubles? 3 2d g