**Answer:**

**Explanation:**

Let hotter star has surface area of A . The cooler star would have surface area 9 times that of hotter star ie 9A , because its radius is 3 times hot star. Let temperature of hot star be T ₁.

Total radiant energy is same for both the star

Using Stefan's formula of black body radiation,

For cold star E = 9A x σ T⁴

For hot star E = A x σ T₁⁴

A x σ T₁⁴ = 9A x σ T⁴

T₁⁴ = (√3)⁴T⁴

T₁ = √3T .

b )

Let the peak intensity wavelength be λ₁ and λ₂ for cold and hot star .

As per wein's law

for cold star , λ₁ T = b ( constant )

for hot star λ₂ √3T = b

dividing

λ₁ T / λ₂ √3T = 1

λ₂ / λ₁ = 1 / √3

<span>The amount of heat energy needed to increase the temperature of a substance by </span>

<span> is given by:

</span>

<span>

where m is the mass of the substance, Cs is its specific heat capacity and </span>

<span> is the increase in temperature of the substance.

In this problem, we have a certain mass m of gold, with specific heat capacity </span>

<span>, to which we add Q=2825 J of energy. Its temperature increases by </span>

<span>. Therefore, if we re-arrange the previous equation, we can find the mass of the block of gold:

</span>

<span>

So, the correct answer is B.</span>

Left.

Forces going left are always negative and forces going right are always postive.

(-)24N. (+)20N

<-----------◼----------->

+20N -24N=

-4N

Left

If the temperature stays the same then:

P1V1=P2V2

so:

97.8*3.75=8P

366.75=8P

P= 45.84 kPa is the new pressure

Finding acceleration= final speed-initial speed/time taken (or A=V-U\T)

Finial speed= 27.8s

Initial speed= 0s

Time taken= 5.15

So..

27.8-0/5.15= 5.40m/s (rounded to two decimal places)