Four blocks EACH of mass m = 10 kg are arranged as shown in the picture, on top of a frictionless table. A hand touching block 1 applies a force of F1h = 90 N to the right. The coefficient of friction between the blocks is sufficient to keep the blocks from moving with respect to each other.
To answer this question, we need to determine the forces acting on each block and analyze the forces on each individual block.
First, let's label the blocks from left to right as block 1, block 2, block 3, and block 4.
1. Block 1: The force applied to block 1 (F1h = 90 N) is the only horizontal force acting on it. There is no vertical force since the block is on the table and is not being pushed or pulled vertically.
2. Block 2: Block 2 experiences two forces - the force applied by block 1 and the force of friction between block 2 and block 3. The force applied by block 1 (F1h = 90 N) acts to the right, and the force of friction opposes the relative motion between block 2 and block 3. Since the blocks are not moving with respect to each other, the force of friction must equal the applied force (F1h = 90 N).
3. Block 3: Block 3 experiences two forces - the force of friction between block 2 and block 3 and the force of friction between block 3 and block 4. The force of friction between block 2 and block 3 (F2-3) opposes the relative motion between them and is equal to the applied force from block 1 (F1h = 90 N). The force of friction between block 3 and block 4 (F3-4) is equal to the applied force from block 2 (F1h = 90 N).
4. Block 4: Block 4 experiences only one force - the force of friction between block 3 and block 4 (F3-4 = 90 N). There are no other horizontal or vertical forces acting on block 4.
Now let's consider the gravitational forces acting on each block. Since all the blocks have the same mass (m = 10 kg), the gravitational force (weight) acting on each block is equal.
The weight of each block is calculated using the formula: weight = mass x acceleration due to gravity.
Therefore, the weight of each block is: Weight = (10 kg) x (9.8 m/s^2) = 98 N.
To summarize the forces acting on each block:
Block 1: Only the applied force F1h = 90 N to the right.
Block 2: Applied force F1h = 90 N to the right and force of friction F2-3 = 90 N to the left.
Block 3: Force of friction F2-3 = 90 N to the right and force of friction F3-4 = 90 N to the left.
Block 4: Only the force of friction F3-4 = 90 N to the right.
Remember that the question states the coefficient of friction between the blocks is sufficient to keep them from moving with respect to each other, so the magnitude of the applied force matches the force of friction.
I hope this explanation helps! If you have any further questions, feel free to ask.