8. At what position does the mass have the greatest acceleration?
1 answer:
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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>
B) The object's velocity doubled.
Explanation:
The graph is missing: find it in attachment.
The kinetic energy of an object is the energy possessed by the object due to its motion. It is calculated as
where
m is the mass of the object
v is the velocity of the object
We notice that:
- The kinetic energy is directly proportional to the mass
- The kinetic energy is proportional to the square of the velocity
In the graph, one of the two quantities (either mass or speed) is represented on the x-axis, while the quantity on the y-axis is the kinetic energy.
First of all, we notice that the relationship is not linear: this means that the quantity on the x-axis cannot be the mass, so it must be the velocity.
Moreover, we notice that when the quantity on the x-axis increases from 1 to 2 (so, it doubles), the kinetic energy increases by a factor of 4. This means that the object's velocity has doubled, therefore
B) The object's velocity doubled.
Learn more about kinetic energy:
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