A student pulls a block over a rough surface with a constant force FP that is at an angle θ above the horizontal, as shown above
. If FP remains constant but the angle θ is increased, which of the following is true at some later time?
A.The force of friction between the block and surface will increase.
B.The force of friction between the block and surface will decrease.
C.The weight of the block will increase.
D.The weight of the block will decrease.
A.The force of friction between the block and surface will increase.
B.The force of friction between the block and surface will decrease.
C.The weight of the block will increase.
D.The weight of the block will decrease.
2 answers:
Answer:
B.The force of friction between the block and surface will decrease.
Explanation:
The force of friction is given by
where is the coefficient of friction and
is the normal force.
When the student pulls on the block with force at an angle
, the normal force on the block becomes
and hence the frictional force becomes
.
Now, as we increase ,
increases which as a result decreases the normal force
, which also means the frictional force decreases; Hence choice B stands true.
<em>P.S: Choice D is tempting but incorrect since the weight </em><em> is independent of the external forces on the block. </em>
You might be interested in
Answer: Option (b) is the correct answer.
Explanation:
Physical equilibrium is defined as a system in which there will occur no change in the physical state of substance. For example, at zero degree celsius water is present in both liquid and solid state as follows.
For a system to be present in physical equilibrium is as follows.
The system must be a closed system.
It should be dynamic in nature.
There will occur no change in measurable property along with change in time.
Thus, we can conclude that ice floats in water at this an example of physical equilibrium because no new substances form when the water molecules change state.
Answer:
Explanation:
A free-body diagram is a sketch of an object of interest with all the surrounding objects stripped away and all of the forces acting on the body shown. The drawing of a free-body diagram is an important step in the solving of mechanics problems since it helps to visualize all the forces acting on a single object. The net external force acting on the object must be obtained in order to apply Newton's Second Law to the motion of the object.
A free-body diagram or isolated-body diagram is useful in problems involving equilibrium of forces.
Free-body diagrams are useful for setting up standard mechanics problems.
