How to calculate an object breaking point or force require to break it? for example, i have a 10 ft rope that has a strength to hold 2000lbs.
when I attach the rope to an object of 1500lb and pull it toward me, (keep it simple with no friction apply) the rope should not be damaged
Now I wrap the rope around the object and have 2 persons identity with the same amount of force pulling toward to themselves. does each person share equal amount of 2000lbs ? which law of physics define this?
 A: You have asked at least two different questions here. I will answer the one in the title of your post.
To solve for when the rope will break, you need to know three things: 1) the magnitude of the load, 2) the cross-sectional area of the rope, and 3) the yield strength of the rope material. 
The yield strength is quoted in terms of pounds of load per square inch of area at the breaking point. So you solve for (magnitude of load)/(cross sectional area of rope). If this number is greater than the yield strength, the rope breaks. 
A: It's really just newton's laws of motion. I guess principally the 3rd one "for every action there is an equal and opposite re-action."
https://en.wikipedia.org/wiki/Newton%27s_laws_of_motion
It depends how fast you accelerate the object, the force must be less than the tension limit in the strings or ropes at all times. (F=ma)
Friction is usually significant in terms of increasing tension, and should not be neglected.
You can gear up the force using pulleys, more details here, https://en.wikipedia.org/wiki/Pulley
