Gravity Gravity- the force that pulls objects towards the Earth Free fall- when the only force acting on an object is gravity – ALL objects in free fall will fall at the same rate of 9.3m/s2 – If you drop a bowling ball and a tennis ball off a building, which one will hit the ground first???
Air Resistance If you drop a tennis ball and a sheet of paper from a building, which one will hit the ground first? Air resistance- a type of fluid friction – Is an upward force – More surface area=more air resistance – Increases with velocity (as objects speed up, air resistance increases)
Air Resistance Eventually, air resistance will equal the force of gravity Forces will become balanced (NO MORE ACCERATION!!) Object will not be able to go any faster as it falls – Called terminal velocity (greatest velocity during free fall)
Universal Law of Gravitation “The force of gravity acts between all objects in the universe.” (all objects will have a gravitational force between them) – Depends on mass and distance – Bigger mass=more gravity – Less distance=more gravity
Gravity Mass vs. weight Are mass and weight the same thing? No! Can the mass of an object change? Can the weight of an object change? Weight- measures the force of gravity on an object Mass- measures how much matter is in an object
How to find weight Weight is a FORCE!!! We will be measuring weight in Newtons Weight= mass x acceleration due to gravity or Weight = mass x 9.8 m/s2
Example Problem… How much would a 59 kg woman weigh on Earth?
Example Problem… A bag of sugar has a mass of 2.26 kg. What is its weight in Newtons? If that same bag of sugar was on the moon, where the acceleration due to gravity(g) is 1.63, how much would the bag of sugar weigh on the moon?