Gravitational Force the gravitational field strength is the amount of force per unit mass acting on an object in the field the gravitational field strength is 9.81 N/kg [down] which is the same as the acceleration due to gravity thus the symbol 𝑔 is used for both to determine the force of gravity acting on an object at the Earth’s surface we use the formula: 𝐹 𝑔 = m 𝑔 3.1 Prac. #2-5

Variations in Field Strength the further you are from the center of the Earth, the smaller the gravitational field strength since the Earth is not a perfect sphere, the g.f.s. will vary according to your location N 9.83 N/kg 9.78 N/kg equator S 9.83 N/kg the equator is actually further from the center of the Earth than the poles (about 21 km) the g.f.s. is less at the equator than poles (refer to table 2 pg. 87) 3.1 Prac. #9,10 Equator Video Real Equator Video

Mass vs. Weight mass is the quantity of matter in an object it does not change according to position on Earth measured in kilograms (kg) weight is the force of gravity on an object ( 𝐹 𝑔 ) to calculate weight use: 𝐹 𝑔 = m 𝑔 measured in Newtons (N) \your weight may vary according to your position on Earth but your mass remains the same Mass vs. Weight Video Mr. Edmonds Mass vs. Weight 3.1 Prac. #6-8 UC #2-9