# APPLICATIONS OF NEWTON'S LAWS

1K10.30 WALKING SPOOL1K20.10 FRICTION OF DIFFERENT SURFACES

1K20.30 STATIC VS SLIDING SURFACES

1K20.35 FRICTION ON INCLINED PLANE

1K30.10 BED OF NAILS

1K10.30 Walking the Spool Pull string at various angles to make spool move forward with rotation, slide without rotating, or move backwards with rotation. Setup Requirements: Off the shelf
Equations: Standard textbook example. The cosine of the angle string makes with horizontal at slide without rotating position = r/R where r is the inner radius.
Safety Issues: none |

1K20.10 Friction of Different Surfaces Pull weights on various surfaces across desktop.Use a spring scale to show how friction depends on roughness of surface. Setup Requirements: Wood, sandpaper,metal and bricks available.
Equations: F= coefficient of friction x normal force
Safety Issues: none |

1K20.30 Static vs. Sliding Friction Using a spring scale and block you can show that static friction is greater than sliding fricton. Coefficient of sliding friction < coefficient of static friction for a given surface. Setup Requirements: Minimal
Equations: Force = coefficient of friction x normal force.
Safety Issues: none |

1K20.35 Friction on Inclined Plane The coefficient of friction can be measured by increasing the angle until object starts to slide. Setup Requirements: Off the shelf
Equations: By splitting the force of gravity into normal component and component along the incline it is found that coefficient of static friction = tangent of angle.
Safety Issues: none |

1K30.10 Bed of Nails (Pressure) Lie down carefully on bed of nails. Spreading your weight out reduces the pressure exerted by any one nail. Compare to putting weight on small heels of high heeled shoes.
Setup Requirements: Off the shelf
Equations: P = F/A Safety Issues: Holes in you and your clothes. |