With an 8-inch wrench and a 2-inch reverse-extension adapter, what is the effective lever arm length from handle to fastener?

With an 8-inch wrench and a 2-inch reverse-extension adapter, what is the effective lever arm length from handle to fastener?

• A. 4 inches
• B. 8 inches
• C. 6 inches
• D. 10 inches

Answer: (C)

Torque depends on the lever arm length—the distance from your hand to the fastener. A reverse-extension adapter sits between the wrench and the fastener but in the opposite orientation, so it shortens that distance by the adapter’s length. With an 8-inch wrench and a 2-inch reverse adapter, the lever arm is 8 − 2 = 6 inches. Therefore, the effective lever arm from handle to fastener is 6 inches. If it were a standard extension, you’d increase the lever arm to 10 inches instead.

Torque depends on the lever arm length—the distance from your hand to the fastener. A reverse-extension adapter sits between the wrench and the fastener but in the opposite orientation, so it shortens that distance by the adapter’s length. With an 8-inch wrench and a 2-inch reverse adapter, the lever arm is 8 − 2 = 6 inches. Therefore, the effective lever arm from handle to fastener is 6 inches. If it were a standard extension, you’d increase the lever arm to 10 inches instead.