Velocity, Acceleration, and Motion

1. Velocity, Acceleration, and Motion • Velocity • How fast an object is going in a given direction • Ex – 30 miles per hour, east • Acceleration • The change in either the speed of an object or its direction

2. Newton’s laws • Newton's First Law of Motion: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it. Often termed simply the "Law of Inertia“ • Newton's Second Law of Motion: The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma. Acceleration and force are vectors in this law the direction of the force vector is the same as the direction of the acceleration vector. • Newton's Third Law of Motion: For every action there is an equal and opposite reaction.

3. Levers • Levers are one of the simple machines that were probably used in prehistoric times. Levers were first described about 260 BC by the ancient Greek mathematician Archimedes (287-212 BC).

4. Levers • A lever is a simple machine that makes work easier for use; it involves moving a load around a pivot using a force. Many of our basic tools use levers, including scissors, pliers, hammer claws, nut crackers and tongs. • In physics, a lever is a rigid object that is used withan appropriate fulcrum or pivot point to multiply the mechanical force that can be applied to another object.

5. Moments Boom Counter balance weight In order to understand Mechanisms better, we need to understand pivots, moments and equilibrium.

6. Equilibrium When something is balanced it is said to be in equilibrium. Pivot point Or fulcrum Fulcrum

7. Moments The Moment of a Force is the force multiplied by the distance from the pivot point. Distance (d) Force (F) Fulcrum Moment = F x d

8. Moments Torque may be represented as shown. Force Pivot Point Torque (turning force) = Force x Distance

9. The Principle of Moments The Principle of Moments states, that for there to be equilibrium, the clockwise moments must equal the anti-clockwise moments. Balanced when f1xd1 = f2xd2 Clockwise Moments = F2 x d2 Anti-clockwise Moments = F1 x d1 If F2 x d2 = F1 x d1 there is equilibrium

10. f1 d2 f2 d1 The Principle of Moments Clockwise Moments = F2 x d2 =20nx1m = 20Nm Anti-clockwise Moments = F1 x d1 = 10Nx2m = 20Nm If F2 x d2 = F1 x d1 there is equilibrium 20Nm = 20Nm, Therefore, the loaded beam is in equilibrium.

11. Levers Class one Examples: Seesaw Crow bar Scissors There are three types or class of lever. Examples: Wheelbarrow Micro switch Brake pedal Class two Example: Shovel Fishing rod Forearm muscles Class three

12. Levers Class One Levers See-saw Crowbar

13. Brake pedal Wheel Barrow Levers Class Two Levers

14. Shovel Fishing rod Levers Class Three Levers

15. Effort Man lifting a Stone with a Lever Lever Load Fulcrum Mechanical Advantage Mechanical Advantage = Load Effort

16. Effort To raise a weight 400N. It was found that the weight could be lifted with an effort of 100N. Load Mechanical Advantage Mechanical Advantage - Calculation What is the Mechanical Advantage of the mechanism? Mechanical Advantage = Load = 400N = 4:1 or 4 Effort 100N