Q16 of 48 Page 38

In a shotput event an athlete throws the shotput of mass 10 kg with an initial speed of 1m s-1 at 45° from a height 1.5 m above ground. Assuming air resistance to be negligible and acceleration due to gravity to be 10 m s -2, the kinetic energy of the shotput when it just reaches the ground will be

Given, h=1.5m, v=1m/s , a= ,m=10kg

If air resistance is negligible then total mechanical energy


remains constant (P.E. at ground is zero)


initial energy=


=


=


=155J


Now,


from law of conservation of mechanical energy,



⇒


∴ final K.E.=155J.


option (d) is correct.

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