Truth or Friction To demonstrate sliding friction, an instructor takes a rectang
ID: 2077900 • Letter: T
Question
Truth or Friction To demonstrate sliding friction, an instructor takes a rectangular block of wood and gives it a sharp push so that the block slides across a smooth table, eventually coming to rest (like the above problem!) The following statements pertain to the motion of the block after it has been released and before it comes to rest (a) True or False: Immediately after the block leaves the instructors hand, the net force on the block is zero. Here and below, please explain your answer and don't just say Tor F.Explanation / Answer
(a) False
The net force will not be zero as the frictional force will be acting on the object
(b) False
The frictional force will be acting opposite to the speed of the object. This frictional force will start reducing the speed of the object.
(c) False
The frictional force is proportional to the weight of the block. This frictional force will provide an opposite acceleration, which will change the rate of change of velocity of the block. In this way, velocity is dependent on the weight of the sliding block.
(d) False
Frictional force and the block's velocity will be dependent. The reason will be similar to (c)
(e) True
The reason is that there is no acceleation in the vertical direction. In this way, both the forces will be equal and opposite.
(f) False.
The frictional force only depends on the friction coefficient and the weight of the block. As both of them doesn't change, the frictional force is constant. This force is opposite to the motion of the block.
(g) True
The friction force will be constant and depend on the kinetic friction coefficient and the normal force.
(h) True
When the velocity becomes zero, the acceleration abruptly goes to zero. Hence the horizontal force will become zero.
(i) False
The normal will be acting always irrespective of the motion of the block.
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