Machines

CD3 M61 - March 5, 2018

LESSON 1

What is Work?

• Work is defined as the product of the magnitude of the displacement of the component of the force parallel to the displacement. In equation, it is written as:

https://www.youtube.com/watch?v=_MR1Dp8-F8w

Simply

W = F x d

when θ = 0°

Where:

F is the magnitude of the constant force

d is the magnitude of the displacement of the object

θ is the angle between the directions of the force and the displacement

• Work is measured in newton-meters and is given a special name, Joule (J).

1 Joule = 1 newton-meter

or

1 J = 1 Nm

• The acceleration due to gravity is the acceleration that acts on all objects that fall within the earth's gravitational field. It is equal to 9. 8 m/s^2

• The force acting on a free-falling object is always equal to the mass of the object multiplied by acceleration due to gravity

Weight = m x 9. 8 m/s^2

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LESSON 2

Simple Machines

• Simple machines - are the machines that we often use at home, in the workplace, and in other places.

• There are 6 types of simple machines, namely:

1. Lever - used for lifting and moving heavy loads, made up of a rigid for supported by

and pivoting about a fulcrum at some point along its length so that an effort at one point can be used to move the load at another point

2. Inclined plane - a plane surface at an angle to a horizontal surface used especially as

a device for lessening the force needed to raise or lower heavy objects

3. Pulley - a simple device for lifting and lowering weights, consisting of a wheel with a

grooved rim over which a rope or bell runs

4. Wheel and axle - made up of a cylindrical axle on which a wheel, concentric with

the axle, is kindly fastened;

5. Wedge - a piece of solid wood, metal or other material tapering to a thin edge, that is

driven into wood to split it, pushed into a narrow gap between moving

parts to immobilize them or used to hold a door open, etc

6. Screw - a small, metal cylinder used as a fastening device, with a thread down the

shaft and a slot in the head, driven into wood, foe example, by rotation using

a screwdriver.

• The most basic types of machines are - Lever and Inclined Plane

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LESSON 3

How do Machines help us Do Work?

• The following are some of the variables that can affect the amount of work a person or a machine can do:

1. Effort - a.k.a. the input force or the force needed to move an object from one place to another

2. Displacement - the distance covered by the load as it moves from one point to another

3. Resistance - a.k.a. the output force or the weight of the load

• Work = force x distance or W = Fd

• Efficiency = (Output work/ Input work) x 100%

https://www.youtube.com/watch?v=vKpsq9xJo7k