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Sergeu [11.5K]
3 years ago
10

A boy jumps from a wall 3m high. What is an estimate of the change in momentum of the boy when he lands without rebounding?

Physics
1 answer:
EastWind [94]3 years ago
8 0
The answer is D. Because the boy jump 3 high
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Identify the correct sequence for the formation and use of coal.
Zanzabum

The correct answer is - A. Plants store solar energy; the plants die; the plants are compressed; solar energy is released;

The plants use the solar energy for their functioning, thus they are one of the biggest natural storage of it. The plants also use the CO2 for the process of photosynthesis that is driven by the solar energy. When the plants die, the things inside them are stored in them, and if they are quickly covered they will remain stored and not get back into the atmosphere. The plants than are compressed, and over time that leads to a change in their composition. After millions of years had passed, the solar energy and CO2 had turned into coal. The coal is heavily used by the humans in the past few centuries, and with its burning the solar energy and the CO2 are released back into the atmosphere from which they came millions of years ago.

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3 years ago
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Amanda goes shopping for light bulbs. In the light bulb aisle, she finds the following incandescent light bulbs. Can you help he
Luden [163]

Answer:

The least efficient light bulb is the first one (25 W - 210 Lumen)

Explanation:

Efficiency can be defined as what you want to obtain over what you need to produce it. In this case Eff= Wattage / Lumen. For each light bulb, their efficiency is: 8.4 / 11.12 / 15.7 Lum/W

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3 years ago
Raul wants to study how pot size affects the growth of plants. To do this, he intends to purchase three different pots of varyin
hram777 [196]

Answer: The answer position may vary. But the correct answer is D. No; Raul changes more than one variable so the results will be invalid.

Explanation:

Raul's experimental set-up will not produce valid results because he intends to change more than one variable.

One variable that Raul will change is the pot size. According to the description, however, Raul will also change one other variable—the type of flower that is planted. Even though Raul plans on using flowers only, he should use the same type of flower in each pot, not different types.

Valid results are only produced when only one variable is changed at a time.

5 0
4 years ago
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A mechanic jacks up the front of a car to an angle of 8.0° with the horizontal in order to change the front tires. the car is 3.
Zina [86]
<span>First draw a free-body diagram. Torque T = Force F x Distance d where force is the component of gravitational force g and d is the lever arm distance to the pivot point. Since the pivot point is at the back tire we subtract that from the length of the car resulting in d = 1.12 - 0.40 = 0.72 meters = d. We are interested in the perpendicular component of the force exerted on the car jack so use sin 8 degrees then T=1130 kg x 9.81 m/s^2 x sin(8 degrees) x0.72 m = 1,110.80 Newton-meters</span>
5 0
4 years ago
A laser used for many applications of hard surface dental work emits 2780-nm wavelength pulses of variable energy (0-300 mJ) abo
Bess [88]

Answer:

a

    n =  1.119 *10^{18} \ photons

b

  P  =  1.6 \ W

Explanation:

From the question we are told that

    The wavelength is  \lambda  =  2780 nm =  2780 *10^{-9} \ m

     The  energy  is  E =  80 mJ  =  80 *10^{-3} \ J

This energy is mathematically represented as

     E   = \frac{n  *  h *  c }{\lambda }

Where  c is the speed of light with a value  c =  3.0 *10^{8} \ m/s

             h is the Planck's  constant with the value  h  =  6.626 *10^{-34} \ J \cdot s

             n is the number of pulses

So

      n =  \frac{E * \lambda }{h * c }

substituting values

       n =  \frac{80 *10^{-3} *  2780 *10^{-9}}{6.626 *10^{-34} * 3.0 *10^{8} }

       n =  1.119 *10^{18} \ photons

Given that the pulses where emitted 20 times in one second then the period of the pulse is

       T  =  \frac{1}{20}

      T = 0.05 \ s

Hence the average power of photons in one 80-mJ pulse during 1 s is mathematically represented as

       P  =  \frac{E}{T}

substituting values

       P  =  \frac{ 80 *10^{-3}}{0.05}

        P  =  1.6 \ W

6 0
3 years ago
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