When the biker is at the top of the ramp, he has a speed of 10 m/s at

In vision, the amplitude of a light wave relates to people's perception of the brightness of a stimulus. To which perceptual dim

den301095 [7]

Answer:

Loudness

Explanation:

In acoustics, loudness is the subjective perception of sound pressure.

5 0

3 years ago

A 80 kg skier grips a moving rope that is powered by an engine and is pulled at constant speed to the top of a 25 degrees hill.

zloy xaker [14]

Answer:

$P=28.085\,hp$

Explanation:

Given that:

mass of 1 skier, $m=80kg$

inclination of hill, $\theta=25^{\circ}$

length of inclined slope, $l=220m$

time taken to reach the top of hill, $t=2.3 min= 138 s$

coefficient of friction, $\mu=0.15$

Now, force normal to the inclined plane:

$F_N=m.g.cos\theta$

$F_N=80\times 9.8\times cos25^{\circ}$

$F_N=710.54\,N$

Frictional force:

$f=\mu.F_N$

$f=0.15\times 710.54$

$f=106.58\,N$

The component of weight along the inclined plane:

$W_l=m.g.sin\theta$

$W_l=80\times 9.8\times sin25^{\circ}$

$W_l=331.33\,N$

Now the total force required along the inclination to move at the top of hill:

$F=f+W_l$

$F=106.58+331.33$

$F=437.91\,N$

Hence the work done:

$W=F.l$

$W=437.91\times 220$

$W=96340.80\,J$

Now power:

$P=\frac{W}{t}$

$P=\frac{96340.80}{138}$

$P=698.12\,W$

So, power required for 30 such bodies:

$P=30\times 698.12$

$P=20943.65\,W$

$P=\frac{20943.65}{745.7}$

$P=28.085\,hp$

8 0

3 years ago

The battery is made up of three 1.5 V cells.

IrinaVladis [17]

Answer: 4.5 V

Explanation:

Given

The voltage of each cell is 1.5 V

If they are connected end to end their potential added to give a higher potential i.e. 1.5+1.5+1.5=4.5 V

6 0

3 years ago

Who was the first president of America

ivolga24 [154]

Answer:George Washington

Explanation:On April 30, 1789, George Washington, standing on the balcony of Federal Hall on Wall Street in New York, took his oath of office as the first President of the United States.

5 0

3 years ago

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Which actions are evidence that a chemical reaction has occurred? Check all that apply. a change in color the formation of a pre

NeTakaya

Answer:

a change in color
the formation of a precipitate
the formation of bubbles

Explanation:

In a chemical reaction, there is always a rearrangement of atoms within the molecules of reactants to form new products. Such a change is different from changes in the physical form of molecules, e.g. shape.

Thus, according to this criteria, only three options are correct in the given question. A change in color is definitely an indication of chemical reaction because the emission of light before and after cannot be changed unless molecules are rearranged to form a new chemical. Likewise, precipitates form when a reaction takes place between chemically dissolved molecules to form less or not dissolvable compounds. In the end, the configuration of bubbles also indicates that the reaction has taken place because new gases are being released.

On the other hand, change in shape is a physical change because the composition doesn't need to also been changed. An example is the ice formation from water. Same is the case with "change of clear liquid to cloudy" because the addition of non-reactive substances could change the nature of liquid to cloudy however the reaction doesn't need to have taken place.

8 0

3 years ago

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