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:
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:
Effort - a.k.a. the input force or the force needed to move an object from one place to another
Displacement - the distance covered by the load as it moves from one point to another
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%
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