Ask question

Ask question

All categories

3 years ago

9

Which statement is true about vectors? a. All quantities in physics are not vectors. b. A vector may have either magnitude or di

rection. c. The vector's length should be proportional to its magnitude. d. Two vectors can be added only if they have the same direction.

1 answer:

dlinn [17]3 years ago

8 0

Yeah yeah ok yeah I saw

You might be interested in

Asap pls hurry will mark brainiest

kifflom [539]

#1. A. Waxing crescent.
#2. 1.
#3. C.
#4. C.

6 0

3 years ago

which two gases in earths atmosphere are believed by scientists to be greenhouse gases that are major contributors to global war

Olenka [21]

Nitrogen and carbon dioxide??

4 0

1 year ago

When a red giant dies, before it becomes a WHITE DWARF (small, dim, hot star) that eventually becomes a BLACK DWARF (remnant, da

vagabundo [1.1K]

some massive black dwarfs may eventually produce <u>supernova explosions. </u>These will occur if pycnonuclear (density-based) fusion processes much of the star to iron, which would lower the Chandrasekhar limit for some black dwarfs below their actual mass.

6 0

3 years ago

Although these quantities vary from one type of cell to another, a cell can be 1.9 μm in diameter with a cell wall 60 nm thick.

DaniilM [7]

Answer: $2(10)^{-9} mg$

Explanation:

We know the total diameter of the cell (assumed spherical) is:

$d=1.9\mu m=1.9(10)^{-6} m$

Then its total radius $r=\frac{d}{2}=\frac{1.9(10)^{-6} m}{2}=9.5(10)^{-7} m$

On the other hand, we know the thickness of the cell wall is $r_{t}=60 nm= 60(10)^{-9} m$ and its density is the same as water ( $\rho=997 kg/m^{3}$ ).

Since density is the relation between the mass $m$ and the volume $V$ :

$\rho=\frac{m}{V}$

The mass is: $m=\rho V$ (1)

Now if we are talking about this cell as a thin spherical shell, its volume will be:

$V=\frac{4}{3}\pi R^{3}$ (2)

Where $R=r-r_{w}=9.5(10)^{-7} m - 60(10)^{-9} m$

Then:

$V=\frac{4}{3}\pi (9.5(10)^{-7} m - 60(10)^{-9} m)^{3}$ (3)

$V=2.952(10)^{-18} m^{3}$ (4)

Substituting (4) in (1):

$m=(997 kg/m^{3})(2.952(10)^{-18} m^{3})$ (5)

$m=2.94(10)^{-15} kg$ (6)

Knowing $1 kg=1000 g$ and $1 mg=0.001 g$ :

$m=2.94(10)^{-15} kg=2(10)^{-9} mg$

7 0

3 years ago

A person walks 40. m east, then 20. m west. He then

Angelina_Jolie [31]

Answer:

ok

Explanation:

3 0

3 years ago