1. Chapter 1.1 Notes Vectors, Force, Inertia, Torque, Mass & Weight

2. Force You can measure force with a Spring scale.

3. Force depends on 2 things; Size or strength of the force and the Direction of the force. Force depends on 2 things; Size or strength of the force and the Direction of the force.Direction

4. Vectors Vs. Scalar A quantity with size and direction is called a Vector. Vector Some quantities are described by size only; they are called Scalars. Scalars

5. A vector is drawn as an arrow. arrow The size of the arrow is proportional to the size of the vector. The arrow points in the direction of the vector.

7. If forces are equal but opposite, they are balanced. If one force is greater than the opposite force, than it is an unbalanced force.

8. The sum of forces is called the net force. If the net force is not zero, the applied forces are unbalanced. If the net forces are zero, the applied forces are balanced and cancel each other out. The object is in equilibrium.

9. If two or more forces act in the same direction, add to get the net force. If two forces act in opposite directions, subtract to get the net force.

11. Never mix units. For example does 30 pounds added to 20 newtons equal 50? NO

12. 3 guys are pulling a rope to the north, each pulling at 200 N. 3 girls are pulling the same rope to the south, each pulling at 150 N. What is the vector sum?

13. 150 S + 150 S + 150 S = 450 South 200 N + 200 N + 200 N = 600 North 600 North – 450 South = 150 North Net Force = 150 North

14. If the forces do not act along a straight line you can use the Graphical method to find the resultant sum. Graphical

15. Also, you can use the Pythagorean theorem to find the resultant sum. Pythagorean The Pythagorean theorem is A 2 + B 2 = C 2

16. If A = 40 N and B equals 30 N, what is the resultant sum (C)?

17. 1. A 2 + B 2 = C 2 2. 2. A=40; B=3040 2 + 30 2 = C 2 3. 3. 1600 + 900 = C 2 4. 4. 2500 = C 2 5. 5. 50 = C First plug in what you know Square A and B Add A and B Square root the answer

18. Newton’s 1 st law of motion: objects will remain at rest or continue to move unless acted on by a force. 1 st1 st Newton’s first law is also called the law of Inertia. Inertia is the property of an object to resist change in motion.

19. Inertia Demos 1.Table Cloth Magic 2.Mardi Gras Beads 3.Wheel Gyroscope a. Rope b. Stool

21. Mass Vs. Weight MassMass is a measure of the total amount of matter contained within an object. Mass WeightWeight is a measure of the force of the Earth’s gravity on the mass of the object. Weight

23. Torque Torque is a quantity that caused rotation in mechanical systems. Torque = the product of Force (F) times the Length of the lever arm. (T = F x L) Units of Torque = Newtons meters (N x m)

24. A torque wrench has a lever arm of.5 m. A force of 100 N is applied at the end of the wrench to tighten a bolt. Find the torque applied to the bolt. 1. 1.Length=.5 m, Force = 100 N 2. 2.Torque = Length x Force 3. 3.Torque =.5 m x 100 N 4. 4.Torque = 50 Nm

25. Opposing torques are common in systems. If opposing torques cancel each other out, the system is a balanced system. A system that is a balanced system that is not moving, will remain at rest. If the system is moving already, the system will continue to rotate at the same speed.