Plutonium has a half life of 2.4 × 104 years. How long does it take for 99.0% of the plutonium to decay?

In which of these situations is convection most likely the main form of heat transfer? A.Warm air from a heater on the first flo

Sergeeva-Olga [200]

All points ate true

But option A is perfect

6 0

3 years ago

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A boat produced water waves of frequency 4 Hz and wavelength 2m, if it reached the shore after 2 seconds how far is the boat fro

kap26 [50]

Answer:

S = 16 m

Explanation:

Given that

The frequency of the water waves, f = 4 Hz

The wavelength of the water waves, λ = 2 m

The time the waves reached the shore, t = 2 s

The relation between the velocity, wavelength, and the frequency of the wave is given by the relation,

v = f λ m/s

Substituting the given values in the above equation,

v = 4 x 2

= 8 m/s

The velocity of the water waves is v = 8 m/s

The distance between the shore and boat is given by

s = v x t

= 8 x 2

= 16 m

Hence, the distance between the boat and the shore is, s = 16 m

7 0

3 years ago

Two points charges are brought closer together,increasing the force between them by a factor of 25.By what factor wa their separ

Roman55 [17]

Answer:

The separation between the charges was decreased by a factor of 0.2

Explanation:

The Coulomb's force between two charges is given by;

$F = \frac{kq^2}{r^2} \\\\let \ kq^2 \ be \ constant\\\\F_1r_1^2 = F_2r_2^2\\\\r_2^2 = \frac{F_1r_1^2}{F_2} \\\\increasing \ the \ force \ between \ them \ by \ factor \ of \ 25\\\\(F_2 = 25F_1)\\\\r_2^2 = \frac{F_1r_1^2}{25F_1}\\\\r_2^2 = \frac{r_1^2}{25}\\\\r_2 = \sqrt{\frac{r_1^2}{25} }\\\\ r_2 = \frac{r_1}{5}$

r₂ = 0.2r₁

Therefore, the separation between the charges was decreased by a factor of 0.2.

6 0

3 years ago

In an experiment, a rectangular block with height h is allowed to float in two separate liquids. In the first liquid, which is w

Amiraneli [1.4K]

Answer:

The relative density of the second liquid is 7.

Explanation:

From archimede's principle we know that the force that a liquid exerts on a object equals to the weight of the liquid that the object displaces.

Let us assume that the volume of the object is 'V'

Thus for the liquid in which the block is completely submerged

The buoyant force should be equal to weight of liquid

Mathematically

$F_{buoyant}=Weight\\\\\rho _{1}\times V\times g=m\times g\\\\\therefore \rho _{1}=\frac{m}{V}...............(i)$

Thus for the liquid in which the block is 1/7 submerged

The buoyant force should be equal to weight of liquid

Mathematically

$F'_{buoyant}=Weight\\\\\rho _{2}\times \frac{V}{7}\times g=m\times g\\\\\therefore \rho _{2}=\frac{7m}{V}.................(ii)$

Comparing equation 'i' and 'ii' we see that

$\rho_{2}=7\times \rho _{1}$

Since the first liquid is water thus $\rho _{1}=1gm/cm^3$

Thus the relative density of the second liquid is 7.

6 0

3 years ago

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Objects can be charged by the transfer of electrons.<br> True<br> False

Sveta_85 [38]

Answer:

True

Explanation:

Whenever electrons are transferred between objects, neutral matter becomes charged. For example, when atoms lose or gain electrons they become charged particles called ions. Three ways electrons can be transferred are conduction, friction, and polarization. In each case, the total charge remains the same.

I tried, hope this helps :)

* I might be wrong though

4 0

3 years ago