The document defines key concepts related to gravity including acceleration due to gravity, gravitational field, gravitational field strength, mass, force, and weight. It provides examples of calculating time, velocity, and weight on Earth and the moon using the formulas and given values of gravitational acceleration. The conclusion is that the acceleration of falling objects is independent of their mass.

2. What is acceleration? What is mass? What is force?

3. When the ball is release, the ball will reach the ground. Why?

4. 2.8 Understanding Gravity

5. Explain and determine the value of acceleration due to gravity Define gravitational field and gravitational strength Define weight Solve problems involving acceleration due to gravity

6. To study the relationship between acceleration of an object and mass Material : Water bottle (2)

7. Conclusion Both objects reach the bottom at the same time The acceleration of an objects does not depend on the mass

8. Definition: Acceleration of an object due to the pull of the gravitational force only. The value of acceleration due to gravity, g is 9.8 ms -2 An object is falls freely under the influence of gravitational force only

11. Definition: Region in which an object experiences a force due to gravitational attraction Any massive object that enters this field will experience a force of attraction This field will get weaker the further you go out from the centre of earth

12. Earth: half size Earth: Half Size GRAVITATIONAL FIELD

13. Gravitational field strength is defined as the gravitational force per unit mass Gravitational field strength of the earth is 9.8 N kg -1 Gravitational field strength of moon is 1.6 N kg -1

14. A ball falls vertically a distance of 125 m to the ground. Using g = 9.8 ms -2 ; calculate: Time the ball takes to fall the first 25m Time the ball takes to reach the ground The velocity of ball before it hits the ground

15. Define: Gravitational force acting on a body Where mass is m and g is gravitational field strength or the acceleration due to gravity Unit = N

16. What is Ali’s weight on the earth and moon if its mass is 70kg? Use g earth = 9.8 ms -2 and g moon = 1.6 ms -2

17. Question time… 1 2 3 4

18. Question 1 Our bodies are pulled down to the earth's surface by Newton’s Weight Gravity

19. Question 2 Object with different mass have ……… acceleration due to gravity Difference Same Zero

20. Question 3 Value of acceleration due to gravity on earth is 9.8 ms -1 True False

21. Question 4 If an object fall with an acceleration due to gravity, the velocity of the object must…… Be constant Continuously change by the same amount each second Continuously change by varying amount each second Continuously decrease

22. Acceleration due to gravity is the acceleration of an object due to the pull of the gravitational force Gravitational field is the region in which an object experiences a force due to gravitational attraction Free fall is an object falls under the influence of gravitational force only Gravitational field strength is the gravitational force per unit mass Weight is the gravitational force acting on a body