Final answer:
To find the force you need to apply to the screw, you can use the formula for mechanical advantage: MA = output force / input force. In this case, the output force is given as 1000 N and the mechanical advantage is 12.5. The input force required is 80 N.
Step-by-step explanation:
To find the force you need to apply to the screw, you can use the formula for mechanical advantage: MA = output force / input force. Rearranging the formula, input force = output force / MA.
In this case, the output force is given as 1000 N and the mechanical advantage is 12.5. Plugging in these values, the input force = 1000 N / 12.5 = 80 N. Therefore, the correct answer is c. 80 N.