Final answer:
Applying force at a 90-degree angle maximizes torque because this condition ensures the force is fully utilized for rotational motion due to the maximum value of the sine function at 90 degrees.
Step-by-step explanation:
Adjusting the grip to apply a force at 90 degrees to the wrench will increase the torque because torque is the product of the force applied and the perpendicular distance from the pivot point (the center of the nut) to the line of action of the force. The formula for torque (τ) is τ = rFsin(θ), where 'r' is the lever arm (the distance from the pivot to the force), 'F' is the applied force, and 'θ' is the angle between the force vector and the lever arm. The maximum torque occurs when the sine of the angle (sin θ) is 1, which happens at 90 degrees, meaning the force is applied perpendicularly. This maximizes the effectiveness of the force in producing rotational motion, hence loosening or tightening a nut more efficiently.