7.7 Example 7

A spring support a block of unknown mass, see image below. If the constant spring is 150 N/m, and this is stretched 5 cm, Which is the mass of the block in grams?

Solution with FisicaLab

Erase the content of the chalkboard and select the SI system, and add one element Spring, one element Block, and one element Stationary reference system. Then add one element Force to the element Spring, and one element Force to the element Block, to make two free body diagrams as show the image below:

The element Stationary reference system write to default the gravity value. To the element Block, write:

m

m @ g

Because the mass is an unknown data, and we want this in grams. To the vertical force applied to the block, that is an unknown data, write:

f

f

To the element Spring, write:

k

150

d

-5 @ cm

The negative sign is because the spring is stretched. To the vertical force applied to the block, that is an unknown data and the same unknown data that to the other force, write:

f

f

Now click in the icon Solve to get the answer.

f = 7.500 N ;  m = 764.526 g ;
Status = success.