Which two types of energy does a book have as it falls to the floor
2 answers:
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Work is done when a force is in the same direction as the object moves.
Explanation:
The work done by a force in moving an object is given by the equation
where
F is the magnitude of the force
d is the displacement of the object
is the angle between the directions of F and d
From the equation, we notice the following:
- Work is done by a force when the force is in the same direction as the object moves. In fact, in this case,
, and so
, which means that the work done simply becomes
- When the force is perpendicular to the motion of the object,
and
, which means that no work done
- Technically, work is also done when the force is not parallel to the motion of the object: in this case, the factor
means that only the component of the force parallel to the direction of motion contributes to do work on the object.
Therefore, the correct answer is
Work is done when a force is in the same direction as the object moves.
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Answer:
The pressure at the top of the step is 129.303 kilopascals.
Explanation:
From Hydrostatics we find that the pressure difference between extremes of the water column is defined by the following formula, which is a particular case of the Bernoulli's Principle ():
(1)
,
- Total pressures at the bottom and at the top, measured in pascals.
- Density of the water, measured in kilograms per cubic meter.
- Height difference of the step, measured in meters.
If we know that ,
,
and
, then the pressure at the top of the step is:
The pressure at the top of the step is 129.303 kilopascals.