A person standing still for a long time feels tired because the force of gravity acts on our body and puts stress on our muscles. so our muscles need energy to do work and keep body balanced and help to stand upright.

6 0

3 years ago

The length of an aluminum wire is quadrupled and the radius is doubled. By which factor does the resistance change?

erik [133]

The resistance of a conductive wire is given by:
$R= \frac{\rho L}{A}$
where
$\rho$ is the material resistivity
$L$ is the wire length
$A$ is the cross-sectional area of the wire

The length of the wire is quadrupled, so if we call L the original length and L' the new length, we can write
$L'=4 L$

Similarly, the radius of the wire is doubled (r'=2r), so the new area is
$A'= \pi (r')^2 = \pi (2r)^2 = 4 \pi r^2 = 4A$

And if we substitute into the equation, we find that the new resistance of the wire is
$R'= \frac{\rho L'}{A'}= \frac{\rho (4L)}{4 A'} = \frac{\rho L}{A}=R$
Therefore, R=R': this means that the resistance of the wire did not change.

7 0

3 years ago

VashaNatasha [74]

Answer:

Displacement is the distance and direction an object is moved. Force and work are directly proportional to each other, while force and displacement are indirectly propotional. The equation showing the relationship is W= Fd. OR Work is a scalar. The rate at which work is done or at which energy is transferred. Work is equal to the force parallel to the displacement.

Explanation:

3 0

3 years ago

How are interference patterns made?

Kisachek [45]

To set up a stable and clear interference pattern, two conditions must be met: The sources of the waves must be coherent, which means they emit identical waves with a constant phase difference.

3 0

3 years ago