Physics, asked by sayushsingh321, 1 year ago

Certain force acting on a 20kg mass changes it velocity from 5ms-'to 2ms- Calculate the work done by the force.


sayushsingh321: please someone answer

Answers

Answered by naz99
28

Mass, m = 20 kg


Initial velocity, u = 5 m/s


Final velocity, v = 2 m/s


Time, t = 1s


From first equation of motion 

      

      v = u + at


or, a = (v - u)/t 

 

a = (2 ms-1 - 5 ms-1)/15



a = -3 ms-2


From third equation of motion,

 


v² - u² = 2as

⇒ (2ms-1)² - (5ms-1)² = 2 x (-3ms-²) x s




⇒          -21 m²s-² = -6 ms-² x s


⇒ s = 7/2 m


Work done = F x s


Force = m x a


Therefore,

 

W = m x a x s

   = 20 kg x (-3ms-²) x 7/2 m

  = -210 Joules

 



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