Simple Machines PDF

IT1919 Simple Machines Examples: Doorknob, motor, electric fan o Pulley – uses a wheel with a groove in it and a rope. It is Fundamentals...

IT1919 Simple Machines Examples: Doorknob, motor, electric fan o Pulley – uses a wheel with a groove in it and a rope. It is Fundamentals used to move the load or change direction of the force. The A simple machine is a basic mechanical device for applying a force following are the types of pulley. and doing work. ▪ Fixed Pulley – The axle is fixed in place and cannot Robots are made up of simple machines that allow them to perform be moved. actions. Types of simple machines: o Lever - is made up of a straight rigid object which pivots on a turning point to move or lift an object. The parts of a lever as are follows: ▪ Bar or Beam – a long plank. It may be wood, metal or any durable material. ▪ Fulcrum - a point on the bar creating a pivot ▪ Effort – applied at one point to move/lift an object ▪ Load – object to be moved/lifted ▪ Movable Pulley: The load is attached to the pulley and both of them can move from place to place. Examples: Seesaw, wheelbarrow, shovel o The three (3) classes of lever indicate that the parts of the lever are not always in the same arrangement. ▪ Class 1: The fulcrum is between the effort and the ▪ Compound Pulley – a combination of pulleys load. (Seesaw) designed to make the effort less than half of the ▪ Class 2: The load is between the effort and the weight of the load. (Block and Tackle) fulcrum. (Wheelbarrow) ▪ Class 3: The effort is between the load and the fulcrum. (Shovel) o Wheel and Axle – is used to move objects across distances. It uses a wheel with a rod attached in the middle as an axle to help it to lift or move loads. 03 Handout 1 *Property of STI  [email protected] Page 1 of 2  IT1919 An inclined plane is a flat surface with one end higher than the Example: Determine the mechanical advantage if 300N force is other. It allows heavy objects to slide up to a higher point or down required to overcome a load of 700N. to a lower point. Solution: FOUT = 700N FIN = 300N MA = FOUT/FIN = 700N/300N = 2.33 Examples: Slide, ramp, funnel Mechanical efficiency is the ratio of the work output to work input. A wedge consists of two (2) inclined planes, giving it a thin end and The formula for mechanical efficiency is: thick end to cut, split, or tighten an object. 𝑊𝑂𝑈𝑇 Examples: Knife, axe, nail 𝑀𝐸 = 𝑥 100% 𝑊𝐼𝑁 A screw is an inclined plane around a cylinder. It can be used to lift Where: ME = Mechanical efficiency things or to hold them together. The parts of a screw as are follows: WOUT = Work output o Shaft – cylinder WIN = Work input o Threads – ridges around the shaft o Pitch – distance between the threads Example: A construction worker puts 25J of energy in to one strike of his hammer on the head of a nail. The energy transferred to driving the nail in to the wood is 8J. What is the efficiency of the construction worker's hammering? Solution: WOUT = 8J WIN = 25J Mechanical Advantage and Mechanical Efficiency 𝑊𝑂𝑈𝑇 Mechanical advantage indicates how much a machine can 𝑀𝐸 = 𝑥 100% 𝑊𝐼𝑁 increase or decrease the force on a load, compare with the effort 8𝐽 force. The formula for mechanical advantage is: = 𝑥 100% 𝐹𝑂𝑈𝑇 25𝐽 𝑀𝐴 = = 0.32 𝑥 100% 𝐹𝐼𝑁 = 32% Where: MA = Mechanical advantage FOUT = Force of the object (output force) References: FIN = Effort to overcome the force of the object (input force) Corke, P. (2017). Robotics: Vision and control. Brisbane: Springer International Publishing AG 2017. Dey, N. & Mukherjee, A. (2016). Embedded systems and robotics with open source tools. Boca If MA is > 1, the output force is greater than the input force. Raton: CRC Press, Taylor & Francis Group. If MA < 1, it does not have a mechanical advantage and requires eSchoolToday. (n.d.). Six types of simple machines. Retrieved from more input force. https://eschooltoday.com/science 03 Handout 1 *Property of STI  [email protected] Page 2 of 2