I. There are two frictional forces acting on the block M1 when it accelerates to
ID: 1705425 • Letter: I
Question
I. There are two frictional forces acting on the block M1 when it accelerates to the right. What are the direction of the forces that act on M1?
II.a) If the two blocks stay together as they accelerate to the right, what do we know of the magnitude of the frictional force acting on block M2? b)What balances the frictional force on block M2 so that it stays in place on block M1?
III. a) If we modify the force F so that the two blocks now move at a constant velocity to the right, what do we know of the magnitude of the frictional force acting on block M2 relative to the new F? b) If both blocks move at a constant speed to the right, what do we know of the magnitude of the frictional force acting between block M1 and the table?
Explanation / Answer
The first friction force that acts on block M1 is between the boxes. Since there is a tendancy for the block M2 to remain in move to the right, then there must be a friction force pointing to the left. There is also a friction force on the block M1 due to the table, and since the Force is pointing to the right, the friction force is opposite the motion and is towards the left. If the two blocks stay together, then the friction force acting on blcok M2 is equal to the Force, because it is accelerating to the right with block M1 rather than moving ahead. The force of the push in the right direction balances the friction force so that it remains on block M1. Since the blocks are moving at a constant velocity, then the force of the push is just enough to overcome the friction force rather than greater than it. So that means that the force of push was decreased to make them move at constant velocity rather than accelerating. So the new force of push is less than the friction force on block M2. We also know that the new force of push is just enough to overcome the force of friction, making it constant velocity, so they are now about the same. So the new force of push is equal to the friction force between M1 and the table.