Practical Applications and System Consolidation

Try these questions

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

1. 1. When solving a bridge beam problem, an engineer takes moments about one of the supports whose reaction is unknown. Why is this a sensible choice?

   • A. It makes translational equilibrium automatically satisfied
   • B. It eliminates that reaction from the moments equation because its perpendicular distance from the pivot is zero
   • C. It turns all clockwise moments into anticlockwise moments
   • D. It doubles the turning moment of the other forces

2. 2. The biceps muscle is attached to the forearm very close to the elbow joint. Why must the muscle exert a force much greater than the weight held in the hand?

   • A. The muscle's effort arm is much shorter than the load's distance from the elbow
   • B. The muscle's effort arm is much longer than the load's distance from the elbow
   • C. The elbow joint is not a fulcrum
   • D. The weight in the hand produces no moment about the elbow

3. 3. On a Nairobi building site, the trolley of a tower crane is moved outwards along the jib while the counterweight stays fixed. To keep the crane balanced, what must happen to the safe payload?

   • A. It can increase, because the moment is larger
   • B. It must decrease, because the payload's perpendicular distance from the mast has increased
   • C. It stays the same, because weight does not change with distance
   • D. It becomes zero at any distance beyond the counterweight

4. 4. A uniform beam 8 m long weighs 3 000 N and rests on piers A and B at its two ends. A truck weighing 5 000 N stops 2 m from pier A. Find the reaction at pier B.

   Type your answer (in N) in the lesson.

5. 5. What is the name given to two equal, parallel and opposite forces whose lines of action do not coincide, and which produce pure rotation without linear acceleration?

   Type your answer in the lesson.

More in Moments and Equilibrium

• ▸States of Equilibrium
• ▸Factors Affecting Stability and Structural Design
• ▸Parallel Forces and Multiple Supports
• ▸Torque, Couples and Resolution of Forces
• ▸Forms of Energy & Conservation
• ▸Concept and Measurement of Work
• ▸Power and the Rate of Doing Work
• ▸Introduction to Machines, Mechanical Advantage and Velocity Ratio

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