Boyle's Law states that when a sample of gas is compressed at a constant temperature, the pressure P and volume V satisfy the equation PV = C, where C is a constant. Suppose that at a certain instant the volume is 900 cm3, the pressure is 100 kPa, and the pressure is increasing at a rate of 40 kPa/min. At what rate is the volume decreasing at this instant?

Respuesta :

Answer:

The value of rate of decrease of volume = - 3600 [tex]\frac{k pa}{min}[/tex]

Step-by-step explanation:

According to Boyle's law P V = C ------- (1)

Pressure ( P ) = 100 k pa = 10 [tex]\frac{N}{cm^{2} }[/tex]

Volume ( V ) = 900 [tex]cm^{3}[/tex]

Put these values in equation ( 1 ) we get,

⇒ C = 10 × 900 = 9000 N-cm = 90 N-m

Differentiate Equation ( 1 ) with respect to time we get,

⇒ V [tex]\frac{dP}{dt}[/tex] + P [tex]\frac{dV}{dt}[/tex] = 0

⇒ V [tex]\frac{dP}{dt}[/tex] = - P [tex]\frac{dV}{dt}[/tex]

[tex]\frac{dV}{dt}[/tex] = - [tex]\frac{V}{P}[/tex] [tex]\frac{dP}{dt}[/tex] ---------- (2)

This equation gives the rate of decrease of volume.

Given that Rate of increase of pressure = [tex]\frac{dP}{dt}[/tex] = 40 [tex]\frac{k pa}{min}[/tex]

C = 90 N-m

P =  [tex]10^{5}[/tex] pa = 10 [tex]\frac{N}{cm^{2} }[/tex]

V = 900 [tex]cm^{3}[/tex]

Put all the above values in equation 2 we get,

⇒  [tex]\frac{dV}{dt}[/tex] = - [tex]\frac{900}{10}[/tex] × 40

⇒  [tex]\frac{dV}{dt}[/tex] = - 3600 [tex]\frac{k pa}{min}[/tex]

This is the value of rate of decrease of volume.