Presentation is loading. Please wait.

Presentation is loading. Please wait.

Do now Can you read the hydraulics pages of your books (p157)?

Similar presentations


Presentation on theme: "Do now Can you read the hydraulics pages of your books (p157)?"— Presentation transcript:

1 Do now Can you read the hydraulics pages of your books (p157)?

2 Today’s lesson Know what the turning effect of a force is Know that the moment of a force depends on force and the distance from the pivot Know the principle of moments

3 What happens when you try to open a door with one finger? Where do you push? Hi, my name is Mr Stick hinges

4 Do you push near the hinges? I can’t do it!

5 Do you push far from the hinges? That’s easier!

6 Moments – Turning forces

7 The turning effect of a force depends on two things; The size of the force Obviously!

8 The turning effect of a force depends on two things; The distance from the pivot (axis of rotation) Not quite so obvious! Axis of rotation

9 Turning effect of a force The turning effect of a force is called the moment of the force The moment is calculated by multiplying the force by the distance from the pivot

10 Turning effect of a force – moment of a force Moment (Nm) = Force (N) x distance from pivot (m) Note the unit is Nm, not N/m!

11 A simple example! nut spanner (wrench) 50 N 0.15 m

12 A simple example! nut spanner (wrench) 50 N 0.15 m Moment = Force x distance from pivot Moment = 50 N x 0.15 m Moment = 7.5 Nm

13 What do you do if the nut won’t move and you can’t push harder?! nut spanner (wrench) 50 N 0.15 m

14 Get a longer spanner! nut spanner (wrench) 50 N 0.25 m Moment = Force x distance from pivot Moment = 50 N x 0.25 m Moment = 12.5 Nm

15 More than one force Take an uneven see-saw for an example Do you think we’ll be safe in this power point? It’s not looking good! pivot

16 If the see-saw is balanced, what must be the weight of the dog on the left? pivot 1.2 m2.2 m 110 N ? N

17 The force on the left is trying to turn the see- saw anticlockwise about the pivot pivot 1.2 m2.2 m 110 N ? N

18 The force on the right is trying to turn the see-saw clockwise about the pivot pivot 1.2 m2.2 m 110 N ? N

19 If the see-saw balances, the turning effect anticlockwise must equal the turning effect clockwise pivot 1.2 m2.2 m 110 N ? N Anticlockwise momentclockwise moment=

20 Anticlockwise moment = clockwise moment ? X 1.2 = 110 x 2.2 ? X 1.2 = 242 ? = 242/1.2 ? = 201.7 N pivot 1.2 m2.2 m 110 N ? N Anticlockwise momentclockwise moment=

21 Rotational Equilibrium When there is no resultant moment on an object (when anticlockwise moments = clockwise moments) we say the object is in rotational equilibrium. YouTube - Alan Partridge's Apache office

22 Whew! We seemed to have survived the power point pivot

23 Don’t speak too soon! pivot BOMB

24 pivot BOMB

25 pivot BOMB

26 pivot BOMB

27 pivot

28 Nice one!

29 pivot You’ll have to do some questions now, or he’ll kill me too!

30 pivot Read pages 162 and 163 and make notes. Then try the questions.


Download ppt "Do now Can you read the hydraulics pages of your books (p157)?"

Similar presentations


Ads by Google