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Yuki888 [10]
3 years ago
15

In 2009, usain bolt of jamaica set a world record of 9.58 s in the 100-m dash. what was his average speed? give your answer in k

ilometers per hour.
Physics
1 answer:
geniusboy [140]3 years ago
5 0
<span>Using a calculator, we find that Usain Bolt's average speed over the 100 meter race was about 23.2 miles per hour. Note that some of the numbers in this calculation, namely 100, 3600, and 5280 are exact while 3.28 and 9.63 are only approximate. Since the approximate numbers only have 3 significant digits we only report three digits in the final answer.

</span>
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A solid sphere, a solid disk, and a thin hoop are all released from rest at the top of the incline (h0 = 20.0 cm).
Ede4ka [16]

Answer:

a. The object with the smallest rotational inertia, the thin hoop

b. The object with the smallest rotational inertia, the thin hoop

c.  The rotational speed of the sphere is 55.8 rad/s and Its translational speed is 1.67 m/s

Explanation:

a. Without doing any calculations, decide which object would be spinning the fastest when it gets to the bottom. Explain.

Since the thin has the smallest rotational inertia. This is because, since kinetic energy of a rotating object K = 1/2Iω² where I = rotational inertia and ω = angular speed.

ω = √2K/I

ω ∝ 1/√I

since their kinetic energy is the same, so, the thin hoop which has the smallest rotational inertia spins fastest at the bottom.

b. Again, without doing any calculations, decide which object would get to the bottom first.

Since the acceleration of a rolling object a = gsinФ/(1 + I/MR²), and all three objects have the same kinetic energy, the object with the smallest rotational inertia has the largest acceleration.

This is because a ∝ 1/(1 + I/MR²) and the object with the smallest rotational inertia  has the smallest ratio for I/MR² and conversely small 1 + I/MR² and thus largest acceleration.

So, the object with the smallest rotational inertia gets to the bottom first.

c. Assuming all objects are rolling without slipping, have a mass of 2.00 kg and a radius of 3.00 cm, find the rotational and translational speed at the bottom of the incline of any one of these three objects.

We know the kinetic energy of a rolling object K = 1/2Iω²  + 1/2mv² where I = rotational inertia and ω = angular speed, m = mass and v = velocity of center of mass = rω where r = radius of object

The kinetic energy K = potential energy lost = mgh where h = 20.0 cm = 0.20 m and g = acceleration due to gravity = 9.8 m/s²

So, mgh =  1/2Iω²  + 1/2mv² =  1/2Iω²  + 1/2mr²ω²

Let I = moment of inertia of sphere = 2mr²/5 where r = radius of sphere = 3.00 cm = 0.03 m and m = mass of sphere = 2.00 kg

So, mgh = 1/2Iω²  + 1/2mr²ω²

mgh = 1/2(2mr²/5 )ω²  + 1/2mr²ω²

mgh = mr²ω²/5  + 1/2mr²ω²

mgh = 7mr²ω²/10

gh = 7r²ω²/10

ω² = 10gh/7r²

ω = √(10gh/7) ÷ r

substituting the values of the variables, we have

ω = √(10 × 9.8 m/s² × 0.20 m/7) ÷ 0.03 m

= 1.673 m/s ÷ 0.03 m

= 55.77 rad/s

≅ 55.8 rad/s

So, its rotational speed is 55.8 rad/s

Its translational speed v = rω

= 0.03 m × 55.8 rad/s

= 1.67 m/s

So, its rotational speed is of the sphere is 55.8 rad/s and Its translational speed is 1.67 m/s

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Answer:

THE GROUND IS THE MEDIUM OF SEISMIC WAVES

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This is true!!

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A<br> B <br> C <br> D<br><br> Plz help me.
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Answer:

The correct option is;

{}               Man doing most work   {}    Box gaining the most energy

D   {}                 Y                                          Q

Explanation:

The given parameters of the question are;

The distance the box P is pushed by the Man X = 0

The force the Man X applies to the box P = x N

The distance the box Q is lifted by the Man Y = h > 0 meters

The minimum force the Man Y applies to the box Q = W, the weight of the box

Work done = Force × Distance

Energy gained = Potential energy + Kinetic Energy = (Mass × Gravity × Height = Weight × Height  = W × h) + 1/2 × Mass × Velocity²

The final velocity of either box = 0 m/s (The boxes are at rest on the ground or the shelf)

Therefore, Kinetic energy = 0 J

The work done by Man X = 0 × x = 0 J

The energy gained by the box P = W × 0 = 0 J

The work done by Man Y = W × h = W·h J

The energy gained by the box P = W × h = W·h J

We have, the work done by the man Y = W·h J is more than the work done by the man X = 0 J

The energy gained by the box P = W·h J is more than the energy gained by the box Q = 0 J

Therefore, the correct option is D, Man doing the most work is Y, box gaining the most energy is Q.

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egoroff_w [7]

the answer is radioactive processes within the Earth.

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