Unit 2 Force & Motion Ch. 8 Sec. 3 Simple Machines

Types of Machines simple machine - does work w/ only 1 movement ex. inclined plane, wedge, screw, lever, wheel and axle, pulley compound machine - made up of a combination of simple machines ex. can opener & bike

Inclined Plane inclined plane - slanted surface used to change an object’s elevation ex. ramp makes work easier by… increasing the distance a force is applied increase in length = greater mechanical advantage Mechanical Advantage 𝑴𝑨= 𝒍 𝒉

Wedge wedge - made up of 2 inclined planes and moves ex. knife, axe, front teeth makes work easier by… changing the direction of a force increase in length and thinness = greater mechanical advantage Mechanical Advantage 𝑴𝑨= 𝒍𝒆𝒏𝒈𝒕𝒉 𝒘𝒊𝒅𝒕𝒉/𝒕𝒉𝒊𝒄𝒌𝒏𝒆𝒔𝒔

Screw screw - an inclined plane wrapped around a cylinder ex. screw, base of a light bulb, mouth of a jar makes work easier by… changing the direction of a force more threads = greater mechanical advantage

Wheel & Axle 4) wheel & axle - consists of 2 circular objects of different sizes (larger = wheel; smaller = axle) ex. steering wheel, screwdriver, faucet handle, ferris wheel makes work easier by… increasing a force Mechanical Advantage 𝑴𝑨= 𝒘𝒉𝒆𝒆𝒍 𝒓𝒂𝒅𝒊𝒖𝒔 𝒂𝒙𝒍𝒆 𝒓𝒂𝒅𝒊𝒖𝒔

Lever 5) lever - rigid bar that moves about a fixed point called the fulcrum ex. seesaw, scissors, broom, baseball bat makes work easier by… increasing distance or force, &/or changing direction of a force

3 Classes of Levers 1st Class Levers fulcrum is in-between input force and load ALWAYS changes direction of input force

3 Classes of Levers 2nd Class Levers load is in-between input force and fulcrum does NOT change direction of input force output force > input force

3 Classes of Levers 3rd Class Levers input force is in-between the fulcrum and load do NOT change the direction of the input forces do NOT increase the input force

Mechanical Advantage of Levers

Pulley pulley - a grooved wheel w/ a rope wrapped around it ex. flagpole, window blind makes work easier by… changing direction of a force or increasing a force

Types of Pulleys Fixed: attached to something that does not move, changes the direction of the force (MA = 1) Movable: attached to an object being moved, increase force and distance (MA = 2) Block & Tackles (pulley system): combination of fixed and movable pulley (MA = # of rope segments)