Moments LO: be able to calculate moments 07/03/2016 Write down everything you can remember about moments from Yr 9.

Which tool would you use? 07/03/2016

Levers A lever can be used to raise the edge of heavy objects 07/03/2016 Label the diagram with the following: effort, pivot, load

Turning forces A turning force is called a moment. What 2 things can increase the turning force? –Increasing the size of the force –Increasing the length the force is applied over 07/03/2016

Turning Moments The size of the moment is given by: Moment (in Nm) = force (in N) x PERPENDICULAR distance from pivot (in m) Calculate the following turning moments: 100 Newtons 5 metres 200 Newtons 2 metres

Moment Questions: 07/03/2016

Kerboodle clip 07/03/2016 Engineers

07/03/2016 Turning Moments 100 Newtons200 Newtons 2 metres Total ANTI-CLOCKWISE turning moment = 200x2 = 400Nm Total CLOCKWISE turning moment = 100x2 = 200Nm The anti-clockwise moment is bigger so the seesaw will turn anti-clockwise

07/03/2016 An example question 5 metres 2000 Newtons 800 Newtons ? metres

07/03/2016 Calculate the missing quantity The following are all balanced: 2N 4m2m ??N 5N3N 2m??m 4m ??m 2m 5N 15N

07/03/2016 Balanced or unbalanced?

Challenge Use the newton meter rulers and 10g masses to challenge each other to balance the rulers. Who can come up with the most difficult challenge? 07/03/2016

A recap question Calculate the mass of man in the example given below: 30kg 1.2m0.4m

07/03/2016 1m A hard question… Consider a man walking along a plank of wood on a cliff. 3m Man’s weight = 800N Plank’s weight = 200N How far can he walk over the cliff before the plank tips over? Aaarrgghh Hint: you need to think about where the centre of mass acts for the plank.

Answer: Consider just the plank first but you must remember that it’s force will be applied over it’s centre of mass on each side. 200N ÷ 3 = 66.6N Clockwise moment = 66.6N x 0.5m (this is the centre on the right hand side and where the centre of mass can be considered to be concentrated) = 33.3Nm Anticlockwise moment = N x 1m (where the centre of mass acts) = 133.3Nm Therefore the difference in moments is 100Nm. The equation can be re-arranged to find the distance the man can move: Distance = moment = 100 = 0.125m force /03/2016

Plenary Typical exam style moment question 07/03/2016