Reaction Forces in Beams and Support Types

How would you plan an investigation to understand the effect of different support types on the direction of reaction forces in a beam, and what evidence would you collect to support your conclusions?

• By setting up beams with various support types, measuring the reaction forces, and comparing the results to theoretical predictions.

• By only reading textbook definitions without performing any experiments.

• By assuming all support types have the same effect on reaction forces.

• By ignoring the direction of reaction forces and focusing only on their magnitude.

Given a simply supported beam with two support points, how would you strategically determine the support reaction forces to ensure static equilibrium? Explain the reasoning and planning involved in your approach.

• By guessing the forces at random and checking if the beam balances.

• By calculating the forces using the magnitude and position of all forces acting on the beam, applying equilibrium equations.

• By ignoring the position of forces and only considering their magnitudes.

• By assuming the support reactions are always equal regardless of load placement.

A beam is supported at two points and subjected to various forces. How would you use evidence and reasoning to verify that the beam is in static equilibrium?

• Check if the sum of all forces and moments acting on the beam equals zero.

• Only check if the beam looks balanced visually.

• Ignore the direction of forces and only add their magnitudes.

• Assume equilibrium without any calculations.

Given a scenario where a car is parked on a bridge, analyze and justify which type of load—concentrated or uniformly distributed—best represents the force exerted by the car on the beam, and explain your reasoning.

• Concentrated load, because the car's weight acts at a specific point on the beam.

• Uniformly distributed load, because the car's weight is spread evenly across the entire bridge.

• Uniformly distributed load, because the car moves along the bridge.

• Concentrated load, because the bridge itself is heavy.

Strategically evaluate why the weight of the bridge itself is considered a uniformly distributed load (UDL) rather than a concentrated load, and discuss the implications for structural design.

• Because the bridge's weight is spread evenly along its entire length, affecting every part of the beam.

• Because the bridge's weight only affects one point on the beam.

• Because the bridge's weight changes depending on the number of vehicles present.

• Because the bridge's weight is negligible compared to other loads.

Given a uniformly distributed load (UDL) of 8 kN/m over a beam of length 6 meters, describe the strategic steps required to convert this UDL into a single concentrated load for moment calculations. Explain your reasoning for each step.

• Calculate the total load by multiplying the UDL by the length, find the midpoint for load application, and redraw the beam with the concentrated load.

• Divide the UDL by the length, place the load at one end, and redraw the beam with the load at the end.

• Ignore the UDL, use the length as the load, and place the load at a random point on the beam.

• Calculate the total load by adding the UDL and length, and distribute the load evenly across the beam.

A beam is subjected to a uniformly distributed load of 8 kN/m over a length of 6 meters. Using strategic reasoning, determine the location where the equivalent concentrated load should be placed and justify your answer.

• At the midpoint of the beam, 3 meters from either end, because the load is uniformly distributed.

• At one end of the beam, because the load starts there.

• At a quarter of the beam length, because it balances the load.

• At three-quarters of the beam length, because it is closer to the support.

A horizontal beam is supported at one end by a roller and at the other end by a pin. If a vertical load is applied at the center of the beam, explain how the reactions at the supports will be distributed and why.

• The roller will provide only a vertical reaction, while the pin will provide both vertical and horizontal reactions.

• Both the roller and the pin will provide only vertical reactions.

• The roller will provide both vertical and horizontal reactions, while the pin will provide only a vertical reaction.

• Both the roller and the pin will provide only horizontal reactions.

Given a structure with a horizontal beam, if the support at one end is replaced from a pin to a roller, how does this change affect the possible directions of the reaction forces at that end? Justify your answer.

• The reaction at the roller end will now only be vertical, whereas the pin could provide both vertical and horizontal reactions.

• The reaction at the roller end will now only be horizontal, whereas the pin could provide only vertical reactions.

• The reaction at the roller end will now be both vertical and horizontal, whereas the pin could provide only vertical reactions.

• There will be no change in the direction of the reaction forces.

A simply supported beam AB is 5 meters long with a point load of 15 kN acting at 3 meters from support A. Using the principle of moments about point A, what is the value of the reaction force at support C (RC)?

• 9 kN

• 6 kN

• 12 kN

• 15 kN