In an internal combustion engine, air at atmostpheric
pressureand a temperature of about 20 degrees celcius is compressed
in thecylinder by a piston to 1/9 of its original volume
(compressionratio = 9.0). estimate the temperature of the
compressed air, assuming the pressure reaches 40 atm.

1302 K or 1029 C

Explanation:

Air at atmospheric pressure has pressure of 1 atm

20 C = 20 + 273 = 293 K

Assume ideal gas, according to the ideal gas law:

Where P1, V1 and T1 are the pressure, volume and temperature of the gas before the compression and P2, V2 and T2 are the pressure, volume and temperature of the gas after the compression

Since the gas is compressed to 1/9 of its original volume, V2/V1 = 1/9:

or 1029 C

it would be kevlar ^^

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me