LIFT BRIDGE/CRANE

I’ve used this crane in the past with my high school classes. Now I’ve turned it into a lift bridge.

The first minute is about a previous subject, so skip to 1:05

So that’s how much force is needed to keep the deck level if the line supporting the deck makes a 30 degree angle with the horizontal.

I mis-spoke at time 4:32 I said “remember its’ not force it’s weight” Boy did I get it backwards. IT IS FORCE

What would change if the angle was 60 degrees?

OK now that you’re familiar with sine and cosine, let’s apply it to a crane.

Boy did I make a mistake. At around 6;00 I said we have to compute how much more torque we need to satisfy the safety factor—torque of the crane body must be 1.5 greater than the torque of the boom/load.

We estimated that we’d need 460 ” lbs more torque. We’d put the extra weight (not torque) 24″ away from the pivot point—SO since Torque – W x D and we know the Dist (24″) then the formula is

460 = W x 24″ I mis-spoke and said 600 not 460 – Sorry