Presentation is loading. Please wait.

Presentation is loading. Please wait.

Newton’s Law of Gravitation. Newton concluded that gravity was a force that acts through even great distances Newton did calculations on the a r of the.

Similar presentations


Presentation on theme: "Newton’s Law of Gravitation. Newton concluded that gravity was a force that acts through even great distances Newton did calculations on the a r of the."— Presentation transcript:

1 Newton’s Law of Gravitation

2 Newton concluded that gravity was a force that acts through even great distances Newton did calculations on the a r of the moon and its F r Found the F r inversely proportional to the square of the radius of orbit

3 Since F r is caused by gravity, the force of gravity is inversely proportional to square of radius Newton also realized that the force of gravity depends on the mass – directly proportional to the mass of the two objects being attracted

4 Law of Universal Gravitation Every part in the universe attracts every other part with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

5 Equation F G = Gm 1 m 2 / r 2 G = universal constant = 6.67 x 10 -11 N m 2 /kg 2

6 Example 1 A 50 kg person and a 75 kg person are sitting on a bench so that their centers are about 50 cm apart. How much gravitational force is there between them?

7 Example 2 What is the force of gravity acting on a 2000 kg spacecraft when it orbits two Earth radii from the Earth’s surface? Radius = 6380 km Mass of earth = 5.98 x 10 24 kg

8 Acceleration Due to Gravity F G = Gm 1 m 2 / r 2 On the earth m 2 is the mass of the earth and m 1 the mass of the object F G = mg mg = Gm 1 m 2 / r 2 m 1 cancels (this is the mass of the object) g = Gm 2 / r 2

9 Example 3 What is the acceleration due to gravity on the moon which has a mass of 7.4 x 10 22 kg and a radius of 1750 km?

10 Example What is the acceleration due to gravity acting on a satellite orbiting at a distance of two earth’s radii from the earth’s surface?

11 The velocity of a satellite keeps it in orbit Even when moving, the satellite is actually accelerating toward the Earth (this is what keeps it in its circular path) Its acceleration results in a curved path which is the same as the curve of the Earth Gravity is providing the centripetal force

12 Perception of Weightlessness There is still gravity acting in a satellite (about 8.9 m/s 2 ), so why do we feel weightless? In an free falling elevator, if the F A is equal to the F G, there is no F N No force is felt feel weightless – called apparent weightlessness

13

14 Weightlessness that you feel in a satellite is like the weightlessness in an elevator The satellite and everything on it are all accelerating toward the earth at the same rate


Download ppt "Newton’s Law of Gravitation. Newton concluded that gravity was a force that acts through even great distances Newton did calculations on the a r of the."

Similar presentations


Ads by Google