A slotted head screw is torqued to 4 Nm using a screw driver having a blade of 5 mm width. The couple force exerted by the blade edges on the screw slot is

Explanation:

To determine the couple force exerted by the blade edges on the screw slot, we need to calculate the force applied by the screwdriver blade and then multiply it by the lever arm.

The formula for torque is given by:

Torque = Force x Lever Arm

In this case, the torque is 4 Nm and the width of the screwdriver blade is 5 mm. However, we need to convert the width of the blade to meters before proceeding with the calculation. 1 mm is equal to 0.001 meters.

Width of the screwdriver blade = 5 mm = 5 x 0.001 m = 0.005 m

Now we can rearrange the formula for torque to solve for force:

Force = Torque / Lever Arm

Force = 4 Nm / 0.005 m = 800 N

Therefore, the couple force exerted by the blade edges on the screw slot is 800 N.

So, the correct answer is option 2.