Al enfriar una placa cuadrada metálica de 8 cm de longitud su lado disminuye un 0.03%
1 answer:
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Answer:
No
Explanation:
The force of tension exerted by the string on the rock acts as centripetal force, so its direction is always towards the centre of the circle.
However, the direction of motion of the rock is always tangential to the circle: this means that the force is always perpendicular to the direction of motion of the rock.
As we know, the work done by a force on an object is
where
F is the magnitude of the force
d is the displacement of the object
is the angle between the force and the displacement
In this situation, F and d are perpendicular, so , therefore
and the work done is zero:
The work done to pull the sled up to the hill is given by
where
F is the intensity of the force
d is the distance where the force is applied.
In our problem, the work done is
and the distance through which the force is applied is 
, so we can calculate the average force by re-arranging the previous equation and by using these data:
where
F is the intensity of the force
d is the distance where the force is applied.
In our problem, the work done is