1 / 20

1.2.3 Equilibrium

1.2.3 Equilibrium. Objective. Draw and use a triangle of forces to represent the equilibrium of three forces acting at a point on an object. Forces. Make a list of all the different types of forces you can think of: Pushes and pulls Weight Friction Drag Upthrust Contact/Reaction Force

coen
Download Presentation

1.2.3 Equilibrium

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 1.2.3 Equilibrium

  2. Objective Draw and use a triangle of forces to represent the equilibrium of three forces acting at a point on an object

  3. Forces Make a list of all the different types of forces you can think of: • Pushes and pulls • Weight • Friction • Drag • Upthrust • Contact/Reaction Force • Tension Write a sentence or two about each force, with examples

  4. Triangle of Forces • Consider the Worked Example on page 61 of “Physics 1”

  5. Turning Forces Explain that a couple is a pair of forces that tends to produce rotation only Define and apply the torque of a couple Define and apply the moment of force

  6. Couple • A couple occurs when two forces are equal and opposite to each other, but are not in the same straight line • Upward force balances downward force • Resultant equals zero • Tend to produce rotation

  7. Couple - definition • A couple is a pair of equal and parallel but opposite forces, which tend to produce rotation only x x

  8. Torque • Describes the turning effect of a couple • Measured in Newton metres • Used to describe turning forces e.g. car engines torque = one of the forces x perpendicular distance between the forces 6 N torque = force x perp. distance = 6 N x 2 m = 12 Nm 2 m 6 N

  9. Moment of a Force • The moment of a force is the turning effect of a single force • Measured in Newton metres • Principle of Moments states that: • For a body in rotational equilibrium, the sum of the clockwise moments equals the sum of the anticlockwise moments x F p x p F

  10. Moment of a Force - definition • The moment of a force is the force multiplied by the perpendicular distance from a stated point

  11. Example A wheelbarrow is loaded as shown • Calculate the force that the gardener needs to exert to hold the legs off the floor • What force is exerted by the ground on the legs of the barrow (taken both together) when the gardener is not holding the handles? 0.20m 400N 0.50m 1.20m

  12. Questions • Physics 1 • SAQ 5.4 to 5.8 • Page 70 question 4

  13. Density Select and use the equation for density ρ = m/V

  14. Density Density = mass volume where density (ρ) is in kg m-3 mass (m) kg volume (V) m3 rho

  15. Density • Density of solids and liquids varies little with temperature • Density of gases varies considerably

  16. Pressure Select and use the equation for pressure – p = F/A where F is the force normal to the area A

  17. Pressure Pressure = force area normal to force where pressure (p) is in Pa or N m-2 force (F) N area (A) m2

  18. Pressure at a depth in a fluid volume = Ah mass m = Ahρ weight = mg = Ahρg = force F pressure on base of column = Ahρg / A = hρg A h Liquid of density ρ

  19. Floating For equilibrium, force upward = weight downward So, • calculate force upward from weight downward

  20. Questions AS Physics 1 • Page 69 • Questions 1, 2 & 3 Assessment • Chapter 5 worksheet • EoC Test – Chapter 5

More Related