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zmey [24]
3 years ago
5

ALWAYS use significant figure rules. Remember that these rules apply to all numbers that are measurements.

Physics
1 answer:
natali 33 [55]3 years ago
8 0

Answer:

Well I'm going to go with A.

Explanation:

As per the question the mass of the boy is 40 kg.

The boy sits on a chair.

We are asked to calculate the force exerted by the boy on the chair at sea level.

The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.

At sea level the acceleration due to gravity g = 9.8 m/s^2

Therefore, the weight of the boy  [m is the mass of the body]

we have m = 40 kg.

                             Therefore, w = 40 kg ×9.8 m/s^2

                                             =392 N kg m/s^2

                                              = 392 N

392 is not an option but I'm guessing you can round down 2 .to option A. 390...?

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Whitch two options are forms of kinetic energy?
valentina_108 [34]

Answer:the witch has nothing to do with the problem

Explanation:

7 0
3 years ago
أسقط عامل حجرة من سطح بناية سقوطأ حرة. أوجد ما يلي :
Ilia_Sergeevich [38]

Answer:

??? i don't no what you just said

Explanation:

7 0
3 years ago
You set your stationary bike on a high 80-N friction-like resistive force and cycle for 30 min at a speed of 8.0 m/s . Your body
stellarik [79]

A) The change in internal chemical energy is 1.15\cdot 10^7 J

B) The time needed is 1 minute

Explanation:

First of all, we start by calculating the power output of you and the bike, given by:

P=Fv

where

F = 80 N is the force that must be applied in order to overcome friction and travel at constant speed

v = 8.0 m/s is the velocity

Substituting,

P=(80)(8.0)=640 W

The energy output is related to the power by the equation

P=\frac{E}{t}

where:

P = 640 W is the power output

E is the energy output

t = 30 min \cdot 60 = 1800 s is the time elapsed

Solving for E,

E=Pt=(640)(1800)=1.15\cdot 10^6 J

Since the body is 10% efficient at converting chemical energy into mechanical work (which is the output energy), this means that the change in internal chemical energy is given by

\Delta E = \frac{E}{0.10}=\frac{1.15\cdot 10^6}{0.10}=1.15\cdot 10^7 J

B)

From the previous part, we found that in a time of

t = 30 min

the amount of internal chemical energy converted is

E=1.15\cdot 10^7 J

Here we want to find the time t' needed to convert an amount of chemical energy of

E'=3.8\cdot 10^5 J

So we can setup the following proportion:

\frac{t}{E}=\frac{t'}{E'}

And solving for t',

t'=\frac{E't}{E}=\frac{(3.8\cdot 10^5)(30)}{1.15\cdot 10^7}=1 min

Learn more about power and energy:

brainly.com/question/7956557

#LearnwithBrainly

3 0
3 years ago
Need help ASAP
VARVARA [1.3K]

Answer:

the correct one is D,  

Ultraviolet, x-ray, gamma ray

Explanation:

Electromagnetism radiation are waves of energy that is expressed by the Planck relationship

          E = h f

where h is the plank constant and f the frequency of the radiation.

Also the speed of light is

          c = λ f

         

we substitute

          E = h c /λ

therefore to damage the cells of the body radiation of appreciable energy is needed

microwave radiation has an energy of 10⁻⁵ eV

infrared radiation                E = 10⁻² eV

visible radiation                   E = 1 to 3 eV

radiation Uv                         E = 3 to 6 eV

X-ray                                    E = 10 eV

 

gamma rays                         E = 10 5 eV

therefore we see that the high energy radiation is gamma rays, x-rays and ultraviolet light.

When checking the answers, the correct one is D

6 0
3 years ago
Derive the value of electric field due to a uniform sphere of charge.
Deffense [45]
<h2>Hey there!</h2>

The Force "F" applied on the unit electric charge "q" at a point describes the electric field.

<h3>☆ Formula to find electric charge:</h3>

  • E = F/q

<h2>Hope it helps </h2>
4 0
2 years ago
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