Two scales and three blocks

[jti3066]

Homework Statement

The weightless horizontal bar in the figure below is in equilibrium. Scale B reads 4.20 kg. The distances in the figure (which is not to scale) are: D1 = 7.5 cm, D2 = 6.0 cm, and D3 = 5.0 cm. The mass of block X is 0.97 kg and the mass of block Y is 1.89 kg. Determine what the reading on scale A must be.

Determine the unspecified mass of block Z.

Here is the diagram:

http://loncapa1.fsu.edu/enc/55/f90d8a024911f78dfa67c5a4b82c4e31d434fffb9e324ad1beb062f2a8a86b5f4b4acacc329e330ca47a2acba58743682d0f6370c013bd229ecc68ff61138f64532270835a981530.gif"

Homework Equations

Not sure..

The Attempt at a Solution

I am not sure where to even begin...Please help me solve this problem

 

[Seannation]

I doubt anyone can help you unless you either upload a stetch of the figure mentioned in the question or type in a diagram using your keyboard.

But from the question I reckon the problem is a bar sitting with two scales on either end. These sorts of problems involve bending moments. Just remember that since the bar is in equilibrium (no net forces acting upon it), the sum of all forces must be 0.

 

[kerimek]

.

I would approach this problem by first identifying all the known variables and their respective values. From the given information, we know that scale B reads 4.20 kg and the distances D1, D2, and D3 are 7.5 cm, 6.0 cm, and 5.0 cm, respectively. We also know that the mass of block X is 0.97 kg and the mass of block Y is 1.89 kg.

Next, I would use the principle of equilibrium, which states that the sum of all forces acting on an object must be equal to zero, to determine the reading on scale A. Since the horizontal bar is in equilibrium, the sum of the forces acting on it must be equal to zero. This means that the weight of the bar (4.20 kg) must be equal to the sum of the weights of blocks X, Y, and Z. Therefore, the reading on scale A must be 4.20 kg minus the weights of blocks X, Y, and Z.

To find the weight of block Z, we can use the formula W = mg, where W is the weight, m is the mass, and g is the acceleration due to gravity (which we can assume to be 9.8 m/s^2). Using the given masses of blocks X and Y, we can calculate their respective weights and subtract them from 4.20 kg to find the weight of block Z. Once we have the weight of block Z, we can use the same formula to find its mass.

In summary, to determine the reading on scale A, we would subtract the weights of blocks X, Y, and Z from 4.20 kg. To find the mass of block Z, we would first calculate its weight using the formula W = mg and then use the same formula to find its mass.