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9 Gravity. Homework RQ: 2, 4, 5, 6, 9, 17, 22. Exs: 3, 4, 10. Intensity. intensity = power/area SI Unit: watts/m 2 Example: the brightness of this screen is determined by the projector-power and the size of the screen. Inverse-Square Relations. Inverse Proportional.
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9 Gravity • Homework • RQ: 2, 4, 5, 6, 9, 17, 22. • Exs: 3, 4, 10.
Intensity • intensity = power/area • SI Unit: watts/m2 • Example: the brightness of this screen is determined by the projector-power and the size of the screen
Inverse Proportional • independent variable doubles and dependent variable halves. • Ex. For constant Net-Force of 10N. • Mass1 = 1kg Accel1 = 10N/1kg = 10m/s/s • Mass2 = 2kg Accel2 = 10N/2kg = 5m/s/s
Inverse-Square Proportional • independent variable doubles and dependent variable quarters. • Ex. Distance = 1m, Force = 64N. • Distance = 2m, Force = 16N. • Distance = 4m, Force = 4N. • Distance = 8m, Force = ?. • /
gravitational force • Newton’s Synthesis: all matter is weakly attracted. • Cavendish Experiment • Torsion Balance
differential pull of gravity • Closer parts of objects more strongly attracted • differential pull causes tides • Tides larger at full and new moon
Summary • Inverse relations, • Inverse-square relations, • How to test for, • Examples of each, • And differential pull.