Gravity Gravity is hugely important and Keeps us

Gravity

Gravity is hugely important, and: Keeps us on the ground Keeps Earth’s atmosphere in place Causes us to need rockets to get into space Keeps moons in orbit around planets Keeps planets in orbit around stars Keeps stars in orbits in galaxies Allows dust to collapse to form new stars Slows the expansion of the Universe

Key ideas about Gravity is the weakest of the four fundamental forces. It’s the only one capable of stretching over huge distances Newton worked out the equation for gravity: What this equation says is that if you’ve got 2 masses a certain distance apart, you can work out the gravitational force between them. You need to multiply the two masses together, and divide this answer by the square of the distance between them. (G is a constant that allows for the different units you are using)

Questions about Gravity mass 1 mass 2 distance 10 4 2 15 6 3 8 4 2 3 4 1 mass 2 distance Which of the 4 rows involved the biggest gravitational force? Which has the smallest? Row 1 force = G x 10 x 4 / (2 x 2) = G x 40 / 4 = G x 10 = 10 G Row 2 force = G x 15 x 6 / (3 x 3) = G x 90 / 9 = G x 10 = 10 G Row 3 force = G x 8 x 4 / (2 x 2) = G x 32 / 4 = G x 8 = 8 G Row 4 force = G x 3 x 4 / (1 x 1) = G x 12 / 1 = G x 12 = 12 G So Row 4 has the largest force, and Row 3 has the smallest force.