# Block A w/ Friction: Find Force & Max Weight

• amm617
In summary, the weight of block A in the figure is 64.2N and the coefficient of static friction is 0.30. The system is in equilibrium with a weight of 11.3N. Using the equation Ff=μN, the friction force exerted on block A is 19.26N. To find the maximum weight for which the system will remain in equilibrium, the normal force (N) is calculated to be 52.9N (64.2N - 11.3N). Therefore, the maximum weight for which the system will remain in equilibrium is 52.9N.
amm617

## Homework Statement

Block A in the figure weighs 64.2N . The coefficient of static friction between the block and the surface on which it rests is 0.30. The weight is 11.3N and the system is in equilibrium.

The picture is a block A, sitting on a table. A string is attached horizontally and then the string breaks off into two separate strings. one connects to the wall with a angle of 45 degrees upward. and the other goes straight down with a weight on the end of it that weighs 11.3 N.

a)Find the friction force exerted on block A.
b)Find the maximum weight for which the system will remain in equilibrium.

Homework Equations Ff=μNThe Attempt at a Solution a)Ff=μN Ff=.30(64.2N) Ff=19.26N b)The maximum weight for which the system will remain in equilibrium is the magnitude of the normal force (N) exerted on block A. The normal force is equal to the weight of the block (64.2N) minus the downward force of the 11.3N weight (i.e., 64.2-11.3=52.9N). Therefore, the maximum weight for which the system will remain in equilibrium is 52.9N.

a) The friction force exerted on block A can be calculated using the formula Ff = μN, where μ is the coefficient of static friction and N is the normal force exerted by the surface on the block. In this case, the normal force is equal to the weight of the block, which is 64.2N. Therefore, the friction force is Ff = 0.30 x 64.2N = 19.26N.

b) To find the maximum weight for which the system will remain in equilibrium, we need to consider the forces acting on the block in the vertical direction. These forces are the weight of the block (64.2N), the weight attached to the string (11.3N), and the vertical component of the tension in the string (Tsinθ, where θ is the angle of the string with respect to the horizontal). Since the system is in equilibrium, the sum of these forces must be equal to zero.

Therefore, we can write the equation: 64.2N + 11.3N + Tsinθ = 0

Solving for T, we get T = -75.5N. Since the tension in the string cannot be negative, the maximum weight that can be supported by the system is 75.5N. This means that if the weight on the string exceeds 75.5N, the system will no longer be in equilibrium and the block will start to move.

## 1. What is the purpose of calculating the force and maximum weight for Block A with friction?

The purpose of calculating the force and maximum weight for Block A with friction is to determine the maximum load or weight that can be placed on the block without causing it to move or slide due to the force of friction.

## 2. What factors affect the force and maximum weight for Block A with friction?

The factors that affect the force and maximum weight for Block A with friction include the coefficient of friction between the block and the surface it is resting on, the weight of the block itself, and the angle of the surface.

## 3. How is the coefficient of friction determined for Block A with friction?

The coefficient of friction for Block A with friction can be determined by dividing the force of friction by the normal force acting on the block. The force of friction can be calculated by multiplying the coefficient of friction by the normal force.

## 4. Is the force and maximum weight for Block A with friction the same on all surfaces?

No, the force and maximum weight for Block A with friction will vary depending on the surface it is resting on. Different surfaces have different coefficients of friction, which can affect the force of friction and ultimately the maximum weight that can be placed on the block.

## 5. How can the force and maximum weight for Block A with friction be increased?

The force and maximum weight for Block A with friction can be increased by decreasing the coefficient of friction between the block and the surface, increasing the weight of the block, or decreasing the angle of the surface.

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