Question

A nasa spacecraft measures the rate r of at which atmospheric pressure on mars decreases with altitude. the result at a certain altitude is: =r0.0421·kpakm−1 convert r to ·jcm−4 .

Answer 1

this is simple question of conversion of unit But as we can see here that one is in kpa or kilo pascal which is a unit of pressure while another is in joule which is unit of energy but if we do the dimension matching we could see that 1pa = 1J/m^3 and 0.0421kpa/km=0.0421pa/m now putting above equation as substitution 0.0421pa/m=0.0421J/m^4 100 cm = 1 m putting it we get R= 4.21Ă—10^-10 J/cm^4

Answer 2

Answer:$4.21 \times 10^{-10} J/cm^4$

$1 kPa= 10^3 Pa$

$1 km=10^5 cm$

$1kPa/km=0.01 Pa/cm$

$1kPa/km=10^{-8} J/cm^4$

$\Rightarrow r= 0.0421 kPa/km= 0.0421 kPa/km \times \frac{10^{-8} J/cm^4}{1 kPa/km}= 0.0421 \times 10^{-8}J/cm^4=4.21 \times 10^{-10} J/cm^4$