Final answer:
If a bolt is overtightened, the bolt itself is likely to fail due to damaged threads, a broken bolt head, or a sheared bolt shaft. Option B is correct.
Step-by-step explanation:
If a bolt is overtightened, the bolt could fail. Overtightening a bolt can cause the threads to strip, the bolt head to break off, or the bolt shaft to shear, compromising the integrity of the bolted connection.
On the other hand, nuts and gaskets might be damaged indirectly due to the excess force, but they would generally fail because the bolt fails first. A torque wrench, which is a tool used to apply a specific torque to a fastener, might be incorrectly calibrated as a secondary issue, but it would not itself fail from overtightening.
When a mechanic puts a length of pipe over the handle of a wrench to remove a very tight bolt, it gives them greater leverage, effectively increasing the torque applied to the bolt.
This is described by the formula torque = force x distance, where increasing the distance from the pivot point allows for more torque with the same amount of force. However, this increased torque can be hazardous, as it makes it easier to exceed the bolt's designed tolerance levels, leading to potential failure.
The correct torque application is crucial in mechanics, as seen in the example of tightening cylinder head bolts on a car with a specified torque of 62.0 N.m. If a mechanic uses a wrench that is 20 cm long, they calculate the needed perpendicular force by rearranging the torque formula to force = torque / distance. So, they would need to exert a perpendicular force of 310 N (62.0 N.m / 0.20 m) to achieve the correct torque.
Additional leverage like using a length of pipe on a wrench increases torque but risks exceeding the bolt's tolerance, causing failure. The recommended torque for a bolt ensures the integrity of the bolted connection and must be carefully observed.