Gravity Chapter 12.2

Gravity Gravity attracts all objects to each other First noticed by issac newton Law of universal gravitation Every object pulls on one another Strength depends on the masses of the objects Depends on the distance between the 2 objects Universal gravitation equation demonstration

Mass has a great effect on gravitational forces Small mass=weak force distance affects gravitational force Small distance=greater force

Weight The total force on an object due to gravity is weight Eg your weight on a scale is the gravitational force exerted by earth on you

Earth has a gravitational force Affects objects on earth most significantly Ignore most other sources

Free fall Objects fall to the ground due to earth’s gravity Newton’s second law Unbalanced force causes an object to accelerate Gravity accelerates it to the ground Called free fall A=9.8 m/s^2 Can use this to calculate any weight using F=ma Measured in newton’s

Terminal velocity Air resistance and weight When air resistance is equal to the weight of an object, it has reached terminal velocity Terminal velocity of a skydiver in freefall is about 200mph

Astronauts Astronauts look weightless right? Actually in free fall Fall toward earth with the same acceleration as earth so they always stay in orbit That’s why they get nauseous all the time Like traveling down the drop of a roller coaster constantly

Projectile motion The astronauts orbiting is a good example of projectile motion Curved path followed by a thrown object near earth’s surface Gravity wants to pull it straight down Inertia wants to keep moving horizontally Eg throwing a baseball Same principles apply to something in orbit But its horizontal acceleration is equal to the force pulling it down