2 Note that this force goes both ways – the Earth is attracted to us. Gravity08/04/2017Gravity is an attractive force that affects anything with mass:Note that this force goes both ways – the Earth is attracted to us.
3 Gravity Gravity depends on 2 things: 2F 1) The mass of the objects F 08/04/2017If you double the mass of one object you double the forceGravity depends on 2 things:2F1) The mass of the objectsF2) The distance between themIf you double the distance the gravitational force divides by 4…FF/4
4 Weight vs. Mass08/04/2017Earth’s Gravitational Field Strength is 10N/kg. In other words, a 1kg mass is pulled downwards by a force of 10N.WgMWeight = Mass x Gravitational Field Strength(in N) (in kg) (in N/kg)What is the weight on Earth of a book with mass 2kg?What is the weight on Earth of an apple with mass 100g?Dave weighs 700N. What is his mass?On the moon the gravitational field strength is 1.6N/kg. What will Dave weigh if he stands on the moon?
5 Words – gravity, smaller, large, lighter Rockets08/04/2017When a rocket flies away from Earth the force needed to keep it accelerating decreases:_____ force needed here_____ force needed hereThis is because…1) As the rocket gets further away from Earth the force of ______ decreases.2) As the rocket burns fuel it gets _______, also decreasing the gravity downwards.Words – gravity, smaller, large, lighter
6 Natural Satellites These planets are all satellites of the sun Mercury 08/04/2017These planets are all satellites of the sunMercuryVenusEarthMarsJupiterSaturnUranusNeptunePluto
7 Artificial Satellites 08/04/2017Artificial satellites have been around for 50 years and have 3 main uses:1) Observation (e.g. Hubble Space Telescope) – these are in orbit high above the Earth and can observe the universe without interference by the ____________2) Communications (e.g. ___, phone, car “SatNav” systems) – these satellites are in “geostationary” orbits. This means that the satellite always stays above ____ ____ point on the Earth and takes a ______ to complete an orbit3) Monitoring (e.g. weather, spy satellites) – these satellites have a “___ _____” orbit and may scan around the Earth several times a dayWords – the same, atmosphere, low polar, TV, day