Question

A mechanic uses a screw driver to install a 1⁄4-20 UNC bolt into a mechanical brace. What is the mechanical advantage of the system? What is the resistance force if the effort force is 5 lb

Answer 1

Answer:

15.7 ; 78.5

Explanation:

Given that

The mechanic use a screw driver to install 1⁄4-20 UNC bolt

And, the effort force is 5lb

We need to find out the mechanical advantage

And, the resistance force

As we know that

The Mechanical advantage of a screw = Circumference ÷ pitch

where,  

Circumference = pi × d

 pi = 3.142, D = diameter

So,  

Circumference = 3.142 × (1 ÷ 4)

= 0.785 in

Now

Pitch = 1 ÷ TPI

Here TPI (thread per inch) = 20

Pitch = 1 ÷  20 = 0.05

So,

Mechanical advantage = 0.785 ÷ 0.05

= 15.7

Now Resistance force if effort force is 5lb

We know that

Mechanical advantage = Fr ÷ Fe

Here

Fe = effort force, Fr = resistance force

15.7 = Fr ÷ 5

Fr = 15.7 × 5

= 78.5 lbs