The 21 kg mass is attached by a cord to a mass hanging over the edge of the table. the frictional force between the mass and the table's surface is 121 n. the mass accelerates at a rate of 0.73 m/s^2 to the right. what is the weight of the hanging block?

147.3 N

Explanation:

Two-Mass Systems

To solve a system where two masses are interacting with each other, we must set up the formulas by applying Newton's second law for each mass. Then, we find the required magnitudes by solving a system of equations.

Our system consists of a hanging object with mass attached to an object of mass lying in a table which applies a known friction force of . We also know the system accelerates at . The situation is pictured in the image below.

Analyzing the forces acting upon mass we have, in the horizontal axis, where movement is taking place:

Where T is the rope's tension force. Now taking the vertical axis of the second mass, we have

The acceleration is negative since it's directed downwards, contrary to the positive default direction (right and up). Subtracting both equations:

Solving for

We know that

so, the above formula becomes

Rearranging and factoring

Solving for

Let's use our known data

Finally, we compute the object's weight

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