Modern Complex Machines and Technological Evolution

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5 questions from this lesson’s quiz. Start the lesson to answer them and see the right answers.

1. 1. In a hydraulic excavator, the hydraulic ram pushes on the dipper arm at a point between the pivot pin and the bucket load. Which class of lever does this arrangement form?

   • A. Class 1 lever
   • B. Class 2 lever
   • C. Class 3 lever
   • D. An inclined plane

2. 2. A passenger lift in Nairobi lifts a net load force of 6000 N at a steady speed of 1.5 m/s. Calculate the useful power output of the motor in watts.

   Type your answer (in W) in the lesson.

3. 3. A workshop machine combines a hydraulic system of velocity ratio 10 with a pulley block of velocity ratio 4. The overall efficiency of the machine is 75%. Calculate its actual mechanical advantage.

   Type your answer in the lesson.

4. 4. A hydraulic lift has an input piston of area 0.02 m^2 and an output ram of area 0.80 m^2. A small force on the input piston can lift a heavy lorry on the ram. Which statement explains why this works?

   • A. The pressure in the enclosed liquid is transmitted equally, so the larger area gives a larger force
   • B. The liquid is compressed so that the force becomes bigger at the ram
   • C. The input piston moves the same distance as the ram, so the work output is greater
   • D. The pressure is greater at the ram because it has a larger area

5. 5. Name the safety device in an excavator that seals oil in the cylinders so that the heavy boom does not drop if a hydraulic hose bursts.

   Type your answer in the lesson.

More in Energy, Work, Power and Machines

• ▸Levers and the Principle of Moments
• ▸Pulleys and Pulley Belt Systems
• ▸Inclined Planes, Wedges and Screws
• ▸Wheel, Gears and Hydraulics

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