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dolphi86 [110]
3 years ago
7

A book starts on a shelf 1 m off of the ground. You then move the book to a higher shelf that is 3 m off of the ground. If the s

ystem gained 20 J of gravitational potential energy, what is the mass of the book?
Physics
1 answer:
JulsSmile [24]3 years ago
4 0

Answer:

Using g = 9.8: 1.02 kg, Using g = 10: 1 kg

Explanation:

E = mgh

20 = m(9.8)(3 - 1)

20 = 9.8m(2)

20 = 19.6m

m = 1.02 kg

I'm now assuming you may be using a g constant of 10, thus the close integer result, in which case the mass would be exactly 1 kilogram.

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A pulley system has an efficiency of 74.2%. If you perform 200 J of work, how
Fudgin [204]

Answer:

C

Explanation:

If a pulley system has an efficiency of 74.2%, then only that fraction of the work performed will be useful. 74.2%=0.742. 0.742*200 is about 148J. Hope this helps!

8 0
2 years ago
IM SOO CONFUSED PLS HELP!! The mass of the nucleus is approximately EQUAL to the mass number multiplied by ____ Atomic Mass unit
nevsk [136]

Answer:

option a.

Explanation:

We can think of an atom as a nucleus (where the protons and neutrons are) and some electrons orbiting it.

We also know that the mass of an electron is a lot smaller than the mass of a proton or the mass of an electron.

So, if all the protons and electrons of an atom are in the nucleus, we know that most of the mass of an atom is in the nucleus of that atom.

Then we define the mass number, which is the total number of protons and neutrons in an atom. Such that the mass of a proton (or a neutron) is almost equal to 1u

Then if we define A as the total number of protons and neutrons, and each one of these weights about 1u

(where u = atomic mass unit)

Then the weight of the nucleus is about A times 1u, or:

A*1u = A atomic mass units.

Then the correct option is:

The mass of the nucleus is approximately EQUAL to the mass number multiplied by __1__ Atomic Mass unit.

option a.

5 0
3 years ago
A bat emitts a sonar sound wave (343 m/s) that bounces off a mosquito 8.42 m away
Varvara68 [4.7K]

The time lapse between when the bat emits the sound and when it hears the echo is 0.05 s.

From the question given above, the following data were obtained:

Velocity of sound (v) = 343 m/s

Distance (x) = 8.42 m

Time (t) =?

We can obtain obtained the time as illustrated below:

v = 2x / t

343 = 2 × 8.42 / t

343 = 16.84 / t

Cross multiply

343 ×  t = 16.84

Divide both side by 343

t = 16.84/343

t = 0.05 s

Thus, the time between  when the bat emits the sound and when it hears the echo is 0.05 s.

<h3>How does a bat know how far away something is?</h3>

A bat emits a sound wave and carefully listens to the echoes that return to it. The returning information is processed by the bat's brain in the same way that we processed our shouting sound with a stopwatch and calculator. The bat's brain determines the distance of an object by measuring how long it takes for a noise to return.

Learn more about time elapses between when the bat emits the sound :

<u>brainly.com/question/16931690</u>

#SPJ4

Correction question:

A bat emits a sonar sound wave (343 m/s) that bounces off a mosquito 8.42 m away. How much time elapses between when the bat emits the sound and when it hears the echo? (Unit = s)

8 0
2 years ago
Are the units of the formula ma = mv2/2 dimensionally consistent? Select the single best answer.
Vesnalui [34]

To solve the problem we will simply perform equivalence between both expressions. We will proceed to place your units and develop your internal operations in case there is any. From there we will compare and look at its consistency

ma = \text{Mass}\times \text{Acceleration}

ma = kg \cdot \frac{m}{s^2}

At the same time we have that

\frac{1}{2}mv^2 = \text{Mass}\times \text{Velocity}^2

\frac{1}{2}mv^2 = kg ( \frac{m}{s})^2

\frac{1}{2}mv^2 = kg \cdot \frac{m^2}{s^2}

Therefore there is not have same units and both are not consistent and the correct answer is B.

5 0
3 years ago
An observation of the red shift of galaxies suggests that the universe is ______ a.. expanding.. b.. contracting.. c.. reversing
harina [27]
<span>An observation of the red shift of galaxies suggests that the universe is expanding. The correct option among all the options that are given in the question is the first option or option "a". I hope that this is the answer that you were looking for and it has actually come to your help.</span>
8 0
3 years ago
Read 2 more answers
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