Final answer:
Mechanics place a pipe over a wrench handle to increase leverage and apply more torque to a bolt, but this can break the bolt. Torque depends on force, leverage distance, and the angle of force application, with 90° providing the maximum torque. Alternatives like socket wrenches or power drills are safer for stubborn nuts.
Step-by-step explanation:
When a mechanic puts a length of pipe over the handle of a wrench to remove a very tight bolt, it increases the leverage applied to the wrench. This is because the effective length of the wrench handle is extended, allowing the mechanic to apply more torque with the same amount of force. However, this higher torque can be hazardous as it may break the bolt if the metal cannot withstand the additional stress.
To calculate the torque applied to a nut, the formula τ = r * F * sin(θ) is used, where τ is the torque, r is the distance from the pivot point to where the force is applied, F is the force applied, and θ is the angle between the force and a line extending from the pivot point. For example, when a 20.00-N force is applied at a 40° angle and at a distance of 0.25 m from the nut, the magnitude of the torque would be calculated using these values. If the angle were 45° instead, then this angle would be used in the calculation. The torque has the largest magnitude when the force is applied perpendicularly to the wrench, meaning at a 90° angle.
If dealing with a rusty nut, additional tools like socket wrenches or a power drill are recommended to provide greater force with less risk of breaking the bolt compared to using a length of pipe for increased leverage.