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2 years ago

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Changes in DNA are known as mutations and can be sometimes produce beneficial changes in population. A mutant form of the normal

ly light-colored peppered moth is dark-colored. The dark-colored moth blends in with soot-covered trees in heavily polluted areas.Why would the dark-colored mutation be beneficial in a polluted area?

1 answer:

Komok [63]2 years ago

4 0

The dark colored moths are beneficial in a polluted area because they have a lesser chance of being eaten since they blend into the trees polluted with soot.

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Newton's law of cooling states that the temperature of an object changes at a rate proportional to the difference between its te

QveST [7]

Answer:

Please see attachment

Explanation:

Please see attachment

8 0

2 years ago

You are using a lightweight rope to pull a sled along level ground. The sled weighs 485 N, the coefficient of kinetic friction b

Bogdan [553]

Answer:

$N=459.01N$

Explanation:

According to Newton's first law:

$N+F_y-W=0$

The component of the force on the y-axis can be obtained through the Pythagorean Theorem. This is because the components are the cathetus of a right triangle and its hypotenuse is the magnitude of the force:

$sin12^\circ=\frac{F_y}{F}\\F_y=Fsin12^\circ$

Replacing and solving for N:

$N=W-Fsin12^\circ\\N=485N-(125N)sin12^\circ\\N=459.01N$

5 0

2 years ago

A box rests on the (horizontal) back of a truck. The coefficient of static friction between the box and the surface on which it

vredina [299]

Answer:

The distance is 11 m.

Explanation:

Given that,

Friction coefficient = 0.24

Time = 3.0 s

Initial velocity = 0

We need to calculate the acceleration

Using newton's second law

$F = ma$ ...(I)

Using formula of friction force

$F= \mu m g$ ....(II)

Put the value of F in the equation (II) from equation (I)

$ma=\mu mg$ ....(III)

$a = \mu g$

Put the value in the equation (III)

$a=0.24\times9.8$

$a=2.352\ m/s^2$

We need to calculate the distance,

Using equation of motion

$s = ut+\dfrac{1}{2}at^2$

$s=0+\dfrac{1}{2}2.352\times(3.0)^2$

$s=10.584\ m\ approx\ 11\ m$

Hence, The distance is 11 m.

3 0

2 years ago

A pair of glasses is dropped from the top of a 32.0m stadium. A pen is dropped 2.Os later. How high above the ground is the pen

Svetllana [295]

Answer:

$h_p = 30.46\ m$

Explanation:

<u>Free Fall Motion</u>

A free-falling object refers to an object that is falling under the sole influence of gravity. If the object is dropped from a certain height h, it moves downwards until it reaches ground level.

The speed vf of the object when a time t has passed is given by:

$v_f=g\cdot t$

Where $g = 9.8 m/s^2$

Similarly, the distance y the object has traveled is calculated as follows:

$\displaystyle y=\frac{g\cdot t^2}{2}$

If we know the height h from which the object was dropped, we can solve the above equation for t:

$\displaystyle t=\sqrt{\frac{2\cdot y}{g}}$

The stadium is h=32 m high. A pair of glasses is dropped from the top and reaches the ground at a time:

$\displaystyle t_1=\sqrt{\frac{2\cdot 32}{9.8}}=2.56\ sec$

The pen is dropped 2 seconds after the glasses. When the glasses hit the ground, the pen has been falling for:

$t_2=2.56 - 2 = 0.56\ sec$

Therefore, it has traveled down a distance:

$\displaystyle y=\frac{9.8\cdot 0.56^2}{2} = 1.54\ m$

Thus, the height of the pen is:

$h_p = 32 - 1.54\Rightarrow h_p=30.46\ m$

8 0

2 years ago

A crane uses a block and tackle to lift a 2200N flagstone to a height of 25m

Cloud [144]

Remember the headline: ENERGY IS NEVER CREATED OR DESTROYED

The amount of energy before and after are always equal. All we ever do with energy is move it around from one place to another.

a). A crane can't create energy. Lifting the same rock in 20 different ways always takes the <u><em>same amount of work</em></u>. It doesn't matter whether one person picks the rock straight up, or 50 people get around it and lift it, or roll it up a ramp, or lift it with 16 pulleys and a mile of rope, or use a giant steam crane.

You want to lift a 2200N weight up 25m, you're going to have to supply

(2200N) x (25m) = <em>55,000 Joules</em> of work.

c). YOU put out 55,000 Joules of energy. It had to GO someplace. Where is it now ? ===> It's the potential energy the rock has now, from being 25m higher than it was before. That <em>55,000 Joules</em> is NOW the potential energy of the rock.

No energy was created or destroyed. It just got moved around.

55,000 Joules of energy began as nuclear energy in the core of the sun. Solar radiation carried it to the Earth. Plants absorbed it, and stored it as chemical energy. You ... or a cow that you ate later ... ate the plants and took the chemical energy. One way or the other, the chemical energy got stored in your blood and fat. When you needed to put it out somewhere, you moved it into your muscles, and they converted it into mechanical energy. Then you used the mechanical energy to exert forces. Today, you used the original 55,000 joules to lift the flagstone, and NOW that energy is in the flagstone, 25 meters up off the ground !

6 0

2 years ago