Freefall

1. Freefall

2. 1. Acceleration Due to Gravity • Galileo did many experiments and proved that if you ignore air resistance: • All objects fall to the earth with uniform acceleration. • Mass of the object does not matter. • Distance above the ground does not matter. • Objects accelerate at 9.81 m/s2 or 32.2 ft/s2. • This varies slightly because of the distance between the object and the center of the earth.

4. Uniform Acceleration

5. Objects dropped will speed up. • Objects thrown up will slow down. • Gravity causes objects to accelerate downward. • Gravity is the attractive force between two objects. • When objects are falling, the only force on them is gravity, and they are in freefall. • Objects in freefall feel “weightless” because the only force is gravity.

6. 2. Frame of Reference going up : +d, +v a = -g = -9.81 m/s2 Slowing Down • Ground level is the reference. ground level going down : -d, -v a = -g = -9.81 m/s2 Speeding Up

7. Acceleration due to gravity : -g = -9.81 m/s2 • Use a = -g = -9.81 m/s2 any time an object is moving up or down! • Assume NO air resistance! • efff.gif

8. Maximum Height Velocity = 0 time = ½ total time +va d = 0 At same height object thrown same velocity, opposite direction d = 0, -va Ground Level

9. Use the same formulas except use a = 9.81 m/s2 • = ½(vf + vi) • d = ½(vf + vi)t • vf = vi + (-g)t • d = vit + ½(-g)t2 • vf2 = vi2 + 2(-g)d