Solving Equilibrium problems

Question 1

1st step for solving an equilibrium problem?

Answer 1

1 - Draw a free-body diagram for the object (show weight of object from the CoG)

Question 2

2nd step for solving an equilibrium problem?

Answer 2

2 - Calculate the moments about one or more points.

Question 3

3rd step for solving an equilibrium problem?

Answer 3

3 - Resolve the forces to find the total force acting in a convenient direction.

Question 4

If 3 forces act on an object what shape needs to be drawn in order to resolve these vectors?

Answer 4

Triangle

Question 5

FInd the values for R2.

Answer 5

• Clockwise moments (downwards) = anti-clockwise moments (upwards)
• (200N x 1m) + (650N x 2m) = R2 x 0.75m

200Nm + 1300Nm = R2 x 0.75m

1500Nm = R2 x 0.75m

R2 = 1500Nm / 0.75m = 2000N

Question 6

Find R1.

Answer 6

anti-clockwise moments = clockwise moments

R1 x 0.75m = (200N x 0.25m) + (650N x 1.25m)

R1 x 0.75m = 862.5 Nm

R1 = 862.5Nm / 0.75m = 1200N (2 s.f)