M8 - Moments

Question 1

Complete the following equation:
Moment = ……………. x …………….

Answer 1

Moment = Perpendicular force x distance

Question 2

What are the steps to complete a moments question about a uniform beam?

Answer 2

• Add reaction forces at beam supports and label R_a, R_b etc
• Mass is applied to be taken at centre of beam (as a uniform beam)
• Resolve vertical forces (they are in equilibrium)
• Take moments clockwise and anticlockwise
• Equate clockwise and anticlockwise moments (due to being in equilibrium)
• If on point of turning, no reaction forces acting on other supports

Question 3

What are the steps to complete a moments question about a ladder?

Answer 3

• Add reaction force at point where ladder meets any surface perpendicular to plane and label R_a, R_b etc
• Mass is taken at centre of the ladder
• Create equations for vertical and horizontal components (both in equilibrium)
• Take moments both clockwise and anticlockwise
• Equate clockwise and anticlockwise components as in equilibrium