A student asks the question: "What makes an object move?" Which of the following is the best

The density of a material in CGS system of units is 4g cm-³. In a system of units in which unit of length is 10 cm and unit of m

butalik [34]

$\sf\underline{Solution:}$

Here , the density of the material is 4g cm³ but it is not given in CGS system.

$\sf{As\:we\:know\:that:}$

$\sf\bold{Density=}$ $\sf\dfrac{Mass}{Volume}$

$\space$

$\sf{Now,according \: to \:the\:question:}$

$\sf\small{Density\:of\:the\:material=4}$ $\sf\dfrac{g}{cm^2}$

$\space$

$\sf{It\:is\:given\:that:}$

In the system of units the mass is 100gram.

$\space$

Hence,

$\sf{The\:mass\:unit\:for\:4g=}$ $\sf\dfrac{4}{100}$ $\sf{units}$

$\space$

In the system of units,the length is 10cm.

Henceforth,

$\sf\small{The\:length \:for\:1cm\:units=}$ $\sf\dfrac{1}{10}$ $\sf{units}$

$\space$

☆ Substitute the required values in the given formula-

$\sf\purple{Density=}$ $\sf\dfrac\purple{Mass}\purple{volume}$

$\space$

$\sf\underline\bold{Density\:of\:the\:material:}$

= $\sf\dfrac{4/100}{1/10^3}$ $\sf\bold{units}$

$\space$

= $\sf\dfrac{4/100}{1/1000}$ $\sf\bold{units}$

$\space$

= $\sf\dfrac{4000}{100}$ $\sf\bold{units}$

$\space$

$\sf\underline\bold\blue{=40\:units}$

$\sf\small{Therefore,option\:2nd\:is\:correct!}$

_______________________________

6 0

2 years ago

The energy from 0.015 moles of octane was used to heat 250 grams of water. The temperature of the water rose from 293.0 K to 371

arsen [322]

Answer : The correct option is, (B) -5448 kJ/mol

Explanation :

First we have to calculate the heat required by water.

$q=m\times c\times (T_2-T_1)$

where,

q = heat required by water = ?

m = mass of water = 250 g

c = specific heat capacity of water = $4.18J/g.K$

$T_1$ = initial temperature of water = 293.0 K

$T_2$ = final temperature of water = 371.2 K

Now put all the given values in the above formula, we get:

$q=250g\times 4.18J/g.K\times (371.2-293.0)K$

$q=81719J$

Now we have to calculate the enthalpy of combustion of octane.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy of combustion of octane = ?

q = heat released = -81719 J

n = moles of octane = 0.015 moles

Now put all the given values in the above formula, we get:

$\Delta H=\frac{-81719J}{0.015mole}$

$\Delta H=-5447933.333J/mol=-5447.9kJ/mol\approx -5448kJ/mol$

Therefore, the enthalpy of combustion of octane is -5448 kJ/mol.

5 0

3 years ago

What TWO things happen to solar radiation that reaches earth?

-Dominant- [34]

The energy of the reflected radiation goes back into outer space. The other 70% of solar radiation that gets to Earth is absorbed. Most of the energy is absorbed by oceans, landforms, and living things.

4 0

2 years ago

Read 2 more answers

A gas sample is held at constant pressure. The gas occupies 3.62 L of volume when the temperature is 21.6°C. Determine the tempe

Serhud [2]

Answer:

281 K

Explanation:

Charles's Law. V1/T1 = V2/T2.

The temperature must be in K = 21.6°C + 273 = 294.6K.

V1T2 = V2T1.

3.62L x T2 = 3.45L x 294.6K

T2 = (3.45 x 294.6) / 3.62 = 1016.4 / 3.62 = B): 281K.

(By direct proportion of volume change: (3.45L / 3.62L) x 294.6K = 281K).

6 0

2 years ago

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a tot

melamori03 [73]

Answer:

H = 1/2 g t^2 time to reach top of trajectory

v = g t time to reach top of trajectory when v is initial speed upwards

v = 5 g = 49 m/s 5 sec upwards and 5 sec downwards

5 0

2 years ago