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3 years ago

Which has the greatest mass, box of rocks box of paperclips or empty box

1 answer:

7 0

The density of an ordinay rock is close to 3 g/cm^3 wihle the density of the paper clips is close to 8 g/cm^3 (the density of steel), then equal apparent volumes (same box) will contain different mass, being of course the mass of the box with paper clips much higher than that of the box with rocks.

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GRADE 5 SCIENCE MYA-2020-2021

Elenna [48]

Answer:

Test it with a blue light that is 45 cm away.

Explanation:

5 0

2 years ago

1(30%). A thin plate black body, insulated at the bottom is placed faced up in a room with wall temperatures of 30 C. Air at 0 C

ch4aika [34]

Explanation:

The given data is as follows.

Heat transfer coefficient (h) = 12 $W/m^{2}.C$

Plate temperature ( $T_{1}$ ) = $30 ^{o}C$ = 303 K

Steady state temperature ( $T_{2}$ ) = ?

Hence, formula applied for steady state is as follows.

$(h \times A \times \Delta T)_{air}$ = $\sigma \times A \times (T^{4}_{1} - T^{4}_{2})_{plate}$

Putting the given values into the above formula as follows.

$(h \times A \times \Delta T)_{air}$ = $\sigma \times A \times (T^{4}_{1} - T^{4}_{2})_{plate}$

$12 \times (T_{2} - 273)$ = $5.67 \times 10^{-8} \times [(30 + 273)^{4} - T^{4}_{2}]$

$T_{2}$ = 282.66 K

= (282.66 -273) $^{o}C$

= 9.66 $^{o}C$

Thus, we can conclude that the steady state temperature will be 9.66 $^{o}C$ .

3 0

3 years ago

Heating 2.40 g of the oxide of metal X (molar mass of X = 55.9 g/mol) in carbon monoxide (CO) yields the pure metal and carbon d

Korolek [52]

Answer:The molecular formula of the oxide of metal be $X_2O_3$ . The balanced equation for the reaction is given by:

$X_2O_3+3CO\rightarrow 3CO_2+2X$

Explanation:

Let the molecular formula of the oxide of metal be $X_2O_y$

$X_2O_y+yCO\rightarrrow yCO_2+2X$

Mass of metal product = 1.68 g

Moles of metal X = $\frac{1.68 g}{55.9 g/mol}=0.03005 mol$

1 mol of metal oxide produces 2 moles of metal X.

Then 0.03005 moles of metal X will be produced by:

$\frac{1}{2}\times 0.03005 mol=0.01502 mol$ of metal oxide

Mass of 0.01502 mol of metal oxide = 2.40 g (given)

$0.01502 mol\times (2\times 55.9 g/mol+y\times 16 g/mol)=2.40 g$

y = 2.999 ≈ 3

The molecular formula of the oxide of metal be $X_2O_3$ . The balanced equation for the reaction is given by:

$X_2O_3+3CO\rightarrow 3CO_2+2X$

8 0

3 years ago

Explain the term contact force and give examples

aliya0001 [1]

Answer & Explanation:

In physics, a contact force is a force that acts at the point of contact between two objects, in contrast to body forces. Contact forces are described by Newton's laws of motion, as with all other forces in dynamics. Contact force is the force in which an object comes in contact with another object. Contact forces are also direct forces. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car up a hill or kicking a ball or pushing a desk across a room are some of the everyday examples where contact forces are at work. In the first case the force is continuously applied by the person on the car, while in the second case the force is delivered in a short impulse.

3 0

3 years ago

What is the second most abundant element in stars? A. helium B. iron C. hydrogen D. oxygen

devlian [24]

The abundance of a chemical element is a measure of the occurrence of the element relative to all other elements in a given environment. Abundance is measured in one of three ways: by the mass-fraction (the same as weight fraction); by the mole-fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases); or by the volume-fraction. Volume-fraction is a common abundance measure in mixed gases such as planetary atmospheres, and is similar in value to molecular mole-fraction for gas mixtures at relatively low densities and pressures, and ideal gas mixtures. Most abundance values in this article are given as mass-fractions.

8 0

3 years ago