DEFINE UNIFORM AND NON UNIFORM VELOCITY
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Answer:
From highest to lowest:
Explanation:
The work done by a force is given by
where:
F is the force applied on the object
d is the displacement of the object
is the angle between the direction of the force and of the displacement
In case 1), the barbell is lifted upward. This means that:
- the force applied is upward
- the displacement of the object is upward
This means that , so the work done is positive:
In case 2), the barbell is held stationary: this means that the displacement is zero,
And therefore, this means that the work done is also zero:
In case 3), the barbell is put down slowly, without dropping it. This means that:
- The force applied is still upward (in fact, the force applied must be upward in order to overcome the force of gravity downward, and avoid the barbell to fall down)
- The displacement of the barbell is downward
This means that , so
, and therefore the work done is negative:
So the ranking from greatest to smallest work is