# Man versus Iron Weight

1. Feb 29, 2008

### Emanresu

http://www2.uah.es/jmc/ai14.pdf

On page 2 of the above pdf there is an example in a box with title 'Acceleration'
which states that there is a difference between a man pulling on a rope with 600N force and an iron weight of 60Kg (g = 10) tied to the rope. The difference being that once the system starts moving the iron weight generates less acceleration. I don't understand the explanation given. Could someone please explain in a different way.

Thanks,

E.

2. Feb 29, 2008

### Staff: Mentor

What pulls the cart is the tension in the rope. Which case produces the greater tension? Hint: If the cart is accelerating, can the tension equal the weight of the hanging mass?

3. Feb 29, 2008

### kdv

The man keeps applying a force of 600 N.

Now consider the weight as it is falling. What is the tension in the rope? Since the weight is accelerating downward, the tension in the rope has to be less than the iron weight therefore the tension is less than 600 N.

4. Feb 29, 2008

### Emanresu

Duh ! It seems so obvious now !

Thanks,

E.