Calculations When engineers, mechanics and equipment operators use fluid power, they need to know how much force their system can apply. These are some of the calculations that they use. Fill in the spaces. 10 cc syringe 5 cc syringe Diameter of piston 14.5 mm 12 mm Diameter of piston in 0.0145 m 0.012 m metres (divide mm by 1000) Radius of piston 0.00725 m 0.006 m (divide diameter by 2) Area of piston (3.14 0.000165 m2 0.000113 m2 × radius squared) Force on piston at 16.5 N 11.3 N 100,000 Pa (multiply area by 100,000) Which piston exerts the larger force at 100 kPa? 10 cc syringe Why does the larger piston exert the larger force? greater surface area on piston (bigger diameter) 10 cc syringe 5 cc syringe In the photo above, a 10 cc syringe is connected to a 5 cc syringe so that the fluid can flow from one to the other. If you push on the piston in the 10 cc syringe, the 5 cc piston syringe’s will move outward. It will move with less force than is pushing on the 10 cc syringe piston, but will move a greater distance. If you push on the piston in the 5 cc syringe, the 10 cc piston will move outwards. syringe’s It will move with more force than is pushing on the 5 cc syringe piston but will move a shorter distance. Fluid power works best when pushing. When you on one syringe you are relying on “pull” ambient air pressure to push the other piston inward. If you pull too hard, then bubbles will form in the hydraulic fluid.
Calculations When engineers, mechanics and equipment operators use fluid power, they need to know how much force their system can apply. These are some of the calculations that they use. Fill in the spaces. 10 cc syringe 5 cc syringe Diameter of piston 14.5 mm 12 mm Diameter of piston in metres (divide mm by 1000) 0.0145 m 0.012 m Radius of piston (divide diameter by 2) 0.00725 m 0.006 m Area of piston (3.14 × radius squared) 0.000165 m2 0.000113 m2 Force on piston at 100,000 Pa (multiply area by 100,000) 16.5 N 11.3 N Which piston exerts the larger force at 100 kPa? 10 cc syringe Why does the larger piston exert the larger force? greater surface area on piston (bigger diameter) 10 cc syringe 5 cc syringe In the photo above, a 10 cc syringe is connected to a 5 cc syringe so that the fluid can flow from one to the other. If you push on the piston in the 10 cc syringe, the 5 cc syringe’s piston will move outward. It will move with less force than is pushing on the 10 cc syringe piston, but will move a greater distance. If you push on the piston in the 5 cc syringe, the 10 cc syringe’s piston will move outwards. It will move with more force than is pushing on the 5 cc syringe piston but will move a shorter distance. Fluid power works best when pushing. When you “pull” on one syringe you are relying on ambient air pressure to push the other piston inward. If you pull too hard, then bubbles will form in the hydraulic fluid.