Stairs because every step u take u use energy and the more steps the more energy
Answer: C
X = Displacement of the spring
Hooke's law: It states that the applied force F is proportional to the displacement of spring .
F ∝ x
Where, x = displacement of spring in meters
F = force, measured in Newtons
In another words The force F is equal to the constant K times the disparagement.
F = k.x
Where k is constant and it depends on elastic material.
Spring has restorative force.
If the spring moves in opposite direction then,
F = - k.x
A negative sign indicates that the spring resists and force is to the left. The compression of the spring is greater than the restoring force.
Example: A mass 'm' stretches a spring at a displacement x.
C. When there is too little resistance and the current increases
Much energy as would Microraptor gui have to expend to fly with a speed of 10 m/s for 1.0 minutes is 486 J.
The first step is to find the energy that Microraptor must release to fly at 10 m/s for 1.0 minutes. The energy that Microraptor must expend to fly can be found using the relationship between Power and Energy.
P = E/t
Where:
P = power (W)
T = time (s)
Now, a minimum of 8.1 W is required to fly at 10 m/s. So, the energy expended in 1 minute (60 seconds) is
P = E/t
E = P x t
E = 8.1 x 60
E = 486 Joules
Thus, the energy that Microraptor must expend to fly at 10 m/s for 1.0 minutes is the 486 J.
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The general formula to calculate the work is:

where F is the force, d is the displacement of the couch, and
is the angle between the direction of the force and the displacement. Let's apply this formula to the different parts of the problem.
(a) Work done by you: in this case, the force applied is parallel to the displacement of the couch, so
and
, therefore the work is just equal to the product between the horizontal force you apply to push the couch and the distance the couch has been moved:

(b) work done by the frictional force: the frictional force has opposite direction to the displacement, therefore
and
. Therefore, we must include a negative sign when we calculate the work done by the frictional force:

(c) The work done by gravity is zero. In fact, gravity (which points downwards) is perpendicular to the displacement of the couch (which is horizontal), therefore
and
: this means
.
(d) Work done by the net force:
The net force is the difference between the horizontal force applied by you and the frictional force:

And the net force is in the same direction of the displacement, so
and
and the work done is
