Machines and Movement Part 1

TRACTOR

  • A machine is a device that makes work easier for human. It enables us to use a small force to overcome a large force .
  • Movement is the ability change position or move from one location to  another. Movement requires energy, which result in work as a result of a force.
  • The simplest machine is the lever.
  • Simple machines are used to make work easier by multiplying, manipulating and directing force easier. Simple machines aren’t very complex and usually have few moving parts, if any. There are six widely accept simple machines. Simple machines combined to make compound or complex machines.

 

LEVERS RThe lever is a movable bar that pivots on a fulcrum attached to a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The input force is the effort and the output force is the load. Levers are divided into three different class. They are first-class lever, second-class lever and third-class lever.
  1. First-class lever: A first-class lever has the fulcrum between the effort (input force) and load (output force).
  2. Second-class lever: A second-class lever has the load between the fulcrum and the effort. for example, a wheelbarrow, a nutcracker, a bottle opener or the brake pedal of a car.
  3. Third-class lever: The third-class lever has the effort between the fulcrum and the load.

Summary

  • The force applied to a lever is the effort.
  • The object the lever is trying to move is called the load.
  • The point about which the lever turns is called the pivot or fulcrum.
  • The lever moves a little effort through a large distance to move a big load through a small distance.   Effort × distance from pivot =   load × distance from pivot.

Distance multiplier machine and force multiplier machine

Distance multipliers are machines that are designed as distance or speed multiplier take a small movement of the effort and multiply it to produce a larger movement of the load. One example of a distance multiplier machine is the fishing rod. A small movement of the effort produce a larger movement of the load. One example of a speed multiplier is the bicycle. When we are pedalling the pedals do not move as far as the wheels, so the distance is being multiplied.
Force multipliers are devices that reduce the amount of force necessary to move an object. Force multipliers are useful for lifting heavy objects or doing other things that require large amounts of force. Some examples of force multipliers are inclined planes and most levers.
Important Notes
  • Energy is the ability to do work. Energy is measured in joules(J).
  • Work is defined as the size of the force being exerted multiplied by the distance moved in the direction of that force.    Work= Force (N) × Distance (m), the unit for work is newton metres, just  like moment of force.  But for work done/ energy converted we refer to these units as joules (abbreviation, capital ‘J’).
  • Force is a push or pull.  Force is measured in newtons ( abbreviation is a capital ‘N’).
  • The turning effect of the force is called a moment. The moment of a force is measured by the perpendicular distance at which it acts from the pivot or fulcrum. Moment (Nm)= force (N) × Distance (m).
  • Principle of moment: if a body in a state of balance, all the clockwise moments about a point added together must equal all the anticlockwise moment  added together.   The sum of clockwise moments = the sum of anticlockwise moments.

Simple machines in various systems

Complex (compound) machines such as bikes are made up of simple machines. Screws are used to hold the pieces together. The wheel of a bike  is a wheel and axle. The pedals are also examples of this simple machine. The pedals are attached to a lever that turns a pulley. The gear shifts and brake handles are levers.
E.g. Cars: The wheel and axle simple machine is used in the car’s axle and drive line. Multiple car components use the lever to make applying force easier. For example, the gear shifting knob and many of the instrument knobs like the windshield wiper control all use lever mechanisms. Plenty of screws are used in cars, including the head and taillights and the very bolts that hold the car together.
simple levers in the mammalian skeleton
Questions
  1. 1)Define machine.
  2. How do machines make work easier?
  3. Name the three types of levers?
  4. How do force and distance multiplier work/carry out there functions?
  5. How much work is done by a person who uses a force of 27.5N to move a grocery buggy 12.3m?
  6. 55, 000J of work is done to move a rock 25m. How much force was applied?
  7. A weight of 10N is a distance of 4 metres from a pivot. The size of the moment can be calculated to be:
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One response to “Machines and Movement Part 1

  1. Its good notes but try to make it detailed to meet standards of Uganda primary schools and teachers who lack adequate references

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