(b) Fig. 3.1 shows a device used for compressing crushed material. 380 mm
120 mm
lever arm
plunger
20N
cylinder
crushed material
cross-sectional
area A
Fig. 3.1
The lever arm rotates about the hinge H at its right-hand end. A force of 20N acts
downwards on the left-hand end of the lever arm. The force Fof the crushed material on
the plunger acts upwards. Ignore the weight of the lever arm.
) Use the clockwise and anticlockwise moments about H to calculate the upward
force Fwhich the crushed material exerts on the plunger. The distances are shown
on Fig. 3.1.
force F=
[3]