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Good Afternoon! 04/20/23• How is it that you can stop a huge
car by just pushing on a pedal? It seems like you would need more force than that doesn’t it?
• The answer will come before the class ends.
Before we get to the Hydraulics
• We need to do the demo that we discussed yesterday.
• Please take out the sheet from yesterday, we’ll finish it and turn it in.
• Put the bag in the beaker and the rubber band around the bag near the mouth of the beaker.
• Now try and get all the air out and then pull up on the bottom of the bag.
Transmitting Pressure in a Fluid
• When force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid.
Hydraulic Devices• In a
hydraulic device, a force applied to one piston increases the fluid pressure equally throughout the fluid.
Hydraulic Devices
• By changing the size of the pistons, the force can be multiplied.
Hydraulic Systems Activity
• Click the Active Art button to open a browser window and access Active Art
about hydraulic systems.
Comparing Hydraulic Lifts
•In the hydraulic device in Figure 15, a force applied to the piston on the left produces a lifting force in the piston on the right. The graph shows the relationship between the applied force and the lifting force for two hydraulic lifts.
Comparing Hydraulic Lifts
–Lift A: 4,000 N; lift B: 2,000 N
• Reading Graphs:
– Suppose a force of 1,000 N is applied to both lifts. Use the graph to determine the lifting force of each lift.
Comparing Hydraulic Lifts
–3,000 N
• Reading Graphs:
– For Lift A, how much force must be applied to lift a 12,000-N object?
Comparing Hydraulic Lifts
–Lift A, because it multiplies force more than lift B.
• Drawing Conclusions:– Which lift would you
choose if you wanted to produce the greater lifting force?
Comparing Hydraulic Lifts
–Lift A: applied force is multiplied by four; lift B: applied force is multiplied by two.
• Interpreting Data:– By how much is the
applied force multiplied for each lift?
Hydraulic Brakes
• The hydraulic brake system of a car multiplies the force exerted on the brake pedal.
How is pressure transmitted in a fluid?
Pressure is transmitted equally to all parts of the fluid.
What is a hydraulic system?
A hydraulic system uses a confined fluid to transmit pressure.
Question Answer
A Few things to think about
Homework
Then work on Questions 21-24 on Page 501