1. Chapter 3 Forces

2. Newton’s Second Law Forces and motion are connected –An object will have greater acceleration if a greater force is applied to it. –The mass of an object and the force applied to it affect acceleration.

3. Newton’s Second Law Acceleration equals net force divided by mass. Friction- force that opposes motion between two surfaces that are touching each other. F=ma

4. Newton’s Second Law –microwelds, areas where surface bumpers stick together, are the source of friction. –Static friction=two surfaces not moving past each other –Sliding friction= opposes the motion of 2 surfaces sliding past each other –Rolling friction=between the rolling object and the surface it rolls on (tire on pavement)

5. Newton’s Second Law Air Resistance-opposes force of gravity –amount depends on object’s shape, size and speed –terminal velocity- forces on a falling object are balanced and the object falls with constant speed upward force exerted on an object falling through air-explains why a brick falls faster than a feather

6. Gravity Law of Gravitation-any two masses exert an attractive force on each other. –One of the 4 basic forces that also include the electromagnetic force, the strong nuclear force, and the weak nuclear force. –Long range force that gives the universe its structure Amount of gravitation force between objects depends on their masses and the distance between them.

7. Gravity Due to inertia, all objects fall with the same acceleration regardless of mass. An object that is in free fall seems to be weightless 9.8 m/s²

8. Gravity Weight –decreases as an object moves away from Earth. –weight results from a force; mass is a measure of how much matter an object contains weight=measure of the force of gravity on an object N mass=measure of the amount of matter in an object g and kg

9. Gravity Objects in the space shuttle float because they have no force supporting them.

10. Gravity Projectiles have horizontal and vertical velocities due to gravity, and follow a curved path. Always curved parallel to Earth’s surface

11. Gravity Acceleration toward the center of a curved path is called centripetal acceleration; it is caused by centripetal force, an unbalanced force. (car rounding a curve) –satellites are anything that moves around another body in a generally circular path. Circle moon=natural satellite space station=artificial satellite

12. The Third Law of Motion To every action force there is an equal and opposite reaction force. –action-reaction forces act on different objects and differ from balanced forces –example= rocket propulsion action force up=reaction force down action force right=reaction force left

13. The Third Law of Motion Momentum-related to how much force is needed to change an object’s motion. momentum=mass times velocity p=mv p=momentumkg X m/s

14. The Third Law of Motion Law of conservation of momentum- momentum can be transferred between objects; momentum is not lost or gained in the transfer When two objects collide…