Presentation Transcript

1. Projectiles and Universal Gravitation

2. Gravitational Force Gravitational force exists between any and all objects that have a mass The strength of the attraction is dependent on the mass of the objects and the distance between them We do not notice the attractive force of gravity of normal objects around us because gravity is a relatively weak force Extreme masses are required in order to create a gravitational force that can be felt
3. Gravitational Force Between Objects Force of gravity between 2 objects is proportional to the mass of each object If the mass of an object doubles, then the force doubles as well
4. Distance and Gravitational Force Distance is measured from the center of one object to the center of the other object Objects that are further away have a weaker gravitational force The decrease in force is related to the inverse, square of the distance
5. What is the relationship between the mass of objects and their gravitational force of attraction? What is the relationship between the distance between 2 objects and their gravitational force of attraction?
6. Distance and Gravitational Force If you double ( increase by 2) the distance that 2 objects are from one another, the force will be ¼ of original force. If you triple (increase by 3) the distance that 2 objects are from one another, the force will be 1/9 the original force Does this sound familiar????
7. Practice: 2 objects are 5 meters apart with an attractive force of 10 Newtons. What happens to the force if they move to 15 meters apart? What is the new force of attraction between them?
8. Newton’s Law of Universal Gravitation This law explains the relationship between force, mass and distance between objects. It uses the gravitational constant (G), which is a value that is the same anywhere in the universe G = 6.67 x N The force calculated is the force felt by both objects
9. The small value of G shows why gravity is weak without a massive object.
10. Practice Use the following information to calculate the force of gravity between Earth and the moon. Mass of Earth is 5.97 x kg and the mass of the moon is 7.34 x kg. The distance between Earth and the moon is 3.84 x m
11. Motion in Two Dimensions We have talked about motion in a straight line Motion with only a magnitude is considered a Scalar Quantity, for example speed. Motion in life however, occurs with turns and curves. This requires 2 different dimensions, an X and a Y
12. Vectors are useful for giving directions
13. Displacement Vector A vector that shows change in position Vector arrow can be scaled to show magnitude Vector arrow also shows direction Can show direction in degrees
14. The Velocity Vector Velocity is a speed with a direction so it is also a vector quantity The arrow will represent the Magnitude and Direction of the vector quantity(velocity) The arrow of a vector can also be scaled
15. Definition of Projectile Any object moving through air and affected only by gravity is called a projectile. Examples include a kicked soccer ball in the air, a stunt car driven off a cliff, and a skier going off a ski jump. Flying objects such as airplanes and birds are not projectiles, because they are affected by forces generated from their own power and not just the force of gravity.
16. Trajectory vs Range of Projectiles Trajectory Path the projectile follows Range The horizontal distance traveled
17. Range of Projectiles
18. Horizontal Velocity Changes An object rolling off of a table becomes a projectile once it leaves the table. There is no net horizontal force, therefore the velocity remains constant in the horizontal direction
19. Vertical Velocity Changes The object is in “free-fall” in the vertical direction as a projectile. The vertical speed will increase by 9.8 m/sec/sec
20. Just like the objects that we talked about in freefall
21. Calculating Distance for Projectiles
22. There is no horizontal distance when directed all vertical There is limited horizontal distance when directed all horizontal Must find a balance between horizontal and vertical