Abicycle pump contains 20cm3 of air at a pressure of 100kpa the air is then pumped in a single stroke through a valve into a tyre if volume 100cm3 whihc contains air at the same pressure. calculate the pressure of the air in the tyre aftee the stroke assume the tyre volume does not change

If we assume also that the temperature of the air does not change, we can use Boyle's Law:
p₁V₁ = p₂V₂

Now, we know: 
p₁ = 100kPa
V₂ = 100cm³ (the volume of the tyre) 
V₁ = 120cm³ (becuse the air is contained inside the tyre AND the pump)

We can solve for p₂:
p₂ = (p₁V₁)/V₂
    = (100×120)/100
    = 120kPa

Therefore your answer is: 120kPa

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