A 17 N horizontal force F pushes a block weighing 6.0 N against a vertical wall. The coefficient of static friction between the wall and the block is 0.68, and the coefficient of kinetic friction is 0.48. Assume that the block is not moving initially. Will the block move? In unit-vector notation, what is the force exerted on the block by the wall?

* Physics/Math - bobpursley, Saturday, February 10, 2007 at 7:10pm
Force friction= mu*17= 11.6N
weight= 6N. Force of friction prevents it from moving.

Ok, so in unit-vector notation the force would be (11.56 N)i + (0 N)j???

No. The wall exerts friction upward, and exerts a counter force of 17 N horizontally.

As a matter of clarification, the force of friction is not 11.6 N, it is 6 N exactly equaling the block weight. The formula mu*force normal is the maximum friction. (f it were greater then 6N the block would move upward, which is not going to happen.

Well if it will not move upward then wouldn't the i component for the final answer be 0 N? That's what I thought it would be but it is incorrect so I am stuck.

the force exerted by the wall, according to newton, would be an equal and opposite reaction, so for the i direction it would be the negative of the force the block places on the wall. the j direction would be the weight of the block

To determine whether the block will move, we need to compare the force of friction between the block and the wall with the maximum force of static friction. The force of friction can be calculated using the formula:

Force of friction = coefficient of static friction * force applied horizontally

Given that the coefficient of static friction is 0.68, and the force applied horizontally is 17 N, we can calculate the force of friction:

Force of friction = 0.68 * 17 N = 11.56 N

Next, we compare the force of friction with the weight of the block, which is 6.0 N. If the force of friction is less than or equal to the weight of the block, the block will not move. In this case, the force of friction is equal to the weight of the block, so the block will not move.

Now let's determine the force exerted on the block by the wall in unit-vector notation. Since the block is not moving, the force of friction equals the force applied by the wall. Therefore, the force exerted on the block by the wall is 11.56 N horizontally in the negative i-direction (opposite to the direction of the force applied by the block) and 6.0 N vertically in the negative j-direction.