Determine the distance of the center of gravity from the end X of the plank?

• looi76
Therefore, the moment due to A and B must be equal to the moment due to the weight (gravity). Using the equation Moment = Force x Perpendicular Distance, we can set up the following equation: (570 N)(0.40 m) = (950 N)(x), where x is the distance from the center of gravity to end X. Solving for x, we get x = 0.24 m. In summary, the plank of wood XY, weighing 950N and measuring 2.50m, has force-meters A and B attached to it at a distance of 0.40m from each end. When the plank is horizontal, force-meter A records 570N. By setting up an equation
looi76

Homework Statement

A non-uniform plank of wood XY is 2.50m long and weighs 950N. Force-meters (spring balances) A and B are attached to the plank at a distance of 0.40m from each end, as illustrated in the Figure below

http://img266.imageshack.us/img266/2377/physicsp23bgh5.png​
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When the plank is horizontal, force-meter A records 570N

(i) Calculate the reading on force-meter B
(ii) Determine the distance of the center of gravity from the end X of the plank.

Homework Equations

Moment = Force x Perpendicular Distance

The Attempt at a Solution

(i) $$A + B = 950N$$
$$B = 950 - 570 = 380N$$

(ii) I don't know how to solve this question, need help!

Last edited by a moderator:
In equilibrium, all the moments (A, B, gravity) cancel out.

To determine the distance of the center of gravity from the end X of the plank, we can use the principle of moments. The center of gravity is the point at which the weight of the object can be considered to act. In other words, if we were to balance the plank at this point, it would remain in equilibrium.

Let's label the distance from end X to the center of gravity as 'd'. We can then write the following equation:

570N x 0.40m = 380N x (2.50m - d)

This equation represents the principle of moments, where the moment on one side of the pivot (force-meter A) is equal to the moment on the other side (force-meter B).

Solving for 'd', we get:

d = 1.15m

Therefore, the center of gravity is located 1.15m from the end X of the plank. This makes sense intuitively, as the center of gravity would be closer to the heavier end of the plank.

Hope this helps!

1. What is the center of gravity?

The center of gravity is the point at which the weight of an object is evenly distributed, allowing it to maintain balance.

2. How is the center of gravity determined?

The center of gravity can be determined by finding the point where the object would balance on a single pivot point, or by calculating the weighted average of the object's individual masses and their respective distances from a reference point.

3. Why is it important to determine the center of gravity?

Determining the center of gravity is important in understanding the stability and balance of an object. It is also crucial in designing structures and vehicles to ensure they are safe and functional.

4. How does the distance of the center of gravity affect an object?

The distance of the center of gravity from a reference point affects the stability and balance of an object. A lower center of gravity provides more stability, while a higher center of gravity can make an object more prone to tipping over.

5. What factors can affect the distance of the center of gravity?

The distance of the center of gravity can be affected by the shape, size, and distribution of an object's mass. Changes in the position or orientation of the object can also alter the distance of the center of gravity.

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