3. In order to change the motion Of an object, you must apply A force to it.

4. A force is the cause of an Acceleration, or the change In an object’s motion. The SI unit of force is the Newton, Labeled with an, N. Force is a VECTOR quantity!

5. The Newton is a derived unit Named after the famous Isaac Newton. It is a derived unit that comes From multiplying acceleration By mass. 1 N = 1kg X 1 m/s 2

6. Forces can act through contact Or at a distance. Contact forces are forces that Arise from the physical Contact of two objects. Field forces are forces that Act across a distance, not Through contact. (i.e. magnets or gravity)

7. In order to show forces on paper, We use force diagrams. A force diagram is a diagram of The objects involved in a situation And the forces exerted on The objects.

8. Another way of showing the Forces involved on an object Is a free body diagram. It is basically a force diagram That has only an isolated object.

9. An object at rest remains at rest, And an object in motion continues In motion with constant velocity (that is, constant speed in a Straight line) unless it experiences A net external force.

10. The tendency of an object not To accelerate is called inertia. The net external force is the Total force resulting from a Combination of external forces On an object; sometimes Called the resultant force.

11. Inertia is directly related to The mass of the object. The greater the mass, the less The object will accelerate under A given force. Equilibrium is the state of a Body in which there is no Change in its motion.

12. The acceleration of an object is Directly proportional to the net External force acting on the Object and inversely proportional To the mass of the object.

13. This is much easier to write As an equation… F = ma

14. FORCESYMBOLDefinitionDirection FrictionFfFf The contact force that acts to oppose sliding motion opposite the direction of sliding NormalFNFN The contact force exerted by a surface on an object Perpendicular to the surface SpringF sp The pull or push a spring exerts on an object Opposite the object at end of spring TensionFtFt The pull exerted by a string or rope when attached to a body Away from object and along string ThrustF thrust A general term for the forces that move rockets or planes Same direction of acceleration WeightFgFg A long-range force due to gravity between objects Straight down to the center of earth

15. The normal force is a contact Force exerted by one object on Another in a direction Perpendicular to the surface Of contact. The normal force is always Perpendicular to the surface, Not necessarily opposite the Force of gravity.

16. F = ma

17. The weight of an object is The magnitude of the force Of gravity acting on that object. w = mg

18. A 5.5 kg watermelon is pushed Across the table. If the Acceleration of the watermelon Is 4.2 m/s 2 to the right, find The net external force. F = 23 N to the right

19. A ball is pushed off with a force Of 13.5 N accelerates at 6.5 m/s 2 to the right. What is The mass of the ball? 2.1 kg

20. The constant velocity that is Reached when the drag force Equals the force of gravity is Called the Terminal Velocity. The terminal velocity of a person Out stretched is about 60 m/s!

21. An interaction pair is a Pair of simultaneous equal but Opposite forces resulting from the Interaction of two objects.

22. If two bodies interact, the Magnitude of the force exerted On object 1 by object 2 is equal To the magnitude of the force Simultaneously exerted on object 2 by object 1, and these two forces Are opposite in direction.

23. This is better stated as For every action, there is an Equal by opposite reaction.

24. When a softball with a mass of 0.18 kg is dropped, its acceleration Is g. What is the force on the Earth due to the ball, and what is Earth’s acceleration? Earth’s mass is 6.0 X 10 24 kg 1.8 N1.8 N2.9 X 10 -25 m/s

25. A 50 kg bucket is being lifted by a Rope. The rope will not break if the Tension is 525 N or less. The bucket Started at rest, and after being lifted 3 m, it is moving at 3 m/s. If the Acceleration is constant, is the Rope in danger of breaking? 570 N, yes it will break!

26. There are only 4 fundamental Forces of nature… Gravitational Forces Electromagnetic Forces The Strong Nuclear Force The Weak Nuclear Force