# Homework Help: Steel rope

1. Aug 16, 2006

### teng125

A steel rope in a cole mine should lift a load of 3500 kg from an underground level of -500 m. The rope is made from steel wire rod. The allowed stress in the steel rope is 60 N/mm².
a) Calculate the necessary section area of the rope and the necessary number of wire rod strands in the steel rope when a wire rod diameter of 2,8 mm is used.

smby pls teach me how to do pls

thanx

2. Aug 16, 2006

### FredGarvin

Let's see some work on your part first.

3. Aug 16, 2006

### teng125

i know the formula stress = mg / area , is "calculate the necessary section area of the rope " means find A=(pi/4)*d^2 ??

while "necessary number of wire rod strands in the steel rope ",i don't know what it means.

4. Aug 16, 2006

### teng125

pls help,i really need to know it

5. Aug 16, 2006

### teng125

anybody knows how to solve this question.....

6. Aug 16, 2006

### Astronuc

Staff Emeritus
Ok, the steel rope is composed of parallel rods. Each rod bears a portion of the load. The allowable stress (60 N/mm²) applys to each rod.

So F = Stress * Area, which means F(max) = Stress(max) * Area

And F(rope) = N * F(rod).

Area(Rope) = N * Area(rod)

Also, the mass (weight) of the rope will contribute to the force (load). So one must calulate the weight of the steel rope, mass = density * volume = density * area * length.

Last edited: Aug 16, 2006
7. Aug 17, 2006

### teng125

so the length is 500m in the case above??

8. Aug 17, 2006

### teng125

so the length is 500m in the case above??

9. Aug 17, 2006

### teng125

i mean the length of the rope is 500m and is the mass of the rope equals to the load that it is going to lift??i can't find the area and weight of the rope

pls help
thanx