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Matter In Our Surroundings

Question
CBSEENSC9005732

Starting from a stationary position Rahul paddles his bicycle to attain a velocity of 6 m/s in 30 seconds. Then he applies brakes such that the velocity of the bicycle comes down to 4 m/s in the next 4 seconds. Calculate the acceleration of the bicycle in both the cases.

Solution
left parenthesis straight i right parenthesis space In space first space case colon space space space

Initial space velocity comma space space straight u space equals space 0

F i n a l space v e l o c i t y comma space straight v space equals space 6 space straight m divided by straight s

Time space taken space to space paddle space the space bicycle comma space straight t space equals space 30 space straight s

therefore space space space space Acceleration comma space space space space straight a space equals space fraction numerator straight v minus straight u over denominator straight t end fraction space equals space fraction numerator 6 minus 0 over denominator 30 end fraction space equals space 0.2 space straight m divided by straight s squared
left parenthesis ii right parenthesis space In space second space case colon space space

I n i t i a l space v e l o c i t y comma space straight u space equals 6 space straight m divided by straight s

Final space velocity comma space straight v space equals space 4 space straight m divided by straight s

Time space taken space to space space space straight t space equals space 4 space straight s

therefore space space space Acceleration comma space space space space straight a space equals space fraction numerator 4 minus 6 over denominator 5 end fraction space equals space 0.4 space straight m divided by straight s squared. space