KinematicsHard

Question

A ball is thrown upwards. It returns to ground describing a parabolic path. Which of the following remains constant?

Options

A.Speed of the ball
B.Kinetic energy of the ball
C.Vertical component of velocity
D.Horizontal component of velocity. 

Solution


V = u + at
Vy = reduced then increases
⇒    V = reduced then increase       (Vx is constant)
⇒  Speed first reduces than increases. So ″A″ is not correct 
KE =  m V2  =  (speed)2     ⇒     ″B″ is not correct   
Vy = changes      ⇒    ″C″ is not correct.
Vx = constt. since gravity is vertically down
⇒    no component of acceleration along the horizontal direction. 
⇒    ″D″ is correct. Ans

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