How to solve this ?

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2 Answers
May 31, 2018

The answer is #option (C)#

Explanation:

Apply Boyle's Law

#P_1V_1=P_2V_2# at #" constant temperature "#

The initial pressure is #P_1=P#

The initial volume is #V_1=V#

The final volume is #V_2=1/2V#

The final pressure is

#P_2=V_1/V_2*P_1=V/(1/2V)*P#

#=2P#

The answer is #option (C)#

May 31, 2018

See below

Explanation:

There is at the very least a typo in this question :(

Assuming that the process is isothermic, then from the ideal gas law:

#pV= p' V' qquad [= nRT = nRT']#

#implies p' = p V /(V') = p V/(V/2) = 2 bb color(red)(p)#

That option is not in the answer key.

More likely in practical terms, the process is adiabatic . In that case:

  • #pV^gamma = " const"#

  • #implies p' = p (V/(V'))^gamma = p * 2^gamma#

#gamma_("air") = 1.4 implies p' = 2.64 \ bb p#

That answer is definitely not in the answer key, so it seems you are expected to make the assumption that the temperature inside the pump remains constant.