Question

A body of mass 0.5 kg is rotating in a vertical circle of radius 2 m. What will be the difference in its kinetic energy at the top and bottom of the circle? (Take g = 9.8 m/s²)

विकल्प

• 10.3 J

• 20.9 J

• 19.6 J

• 50 J

Answer 1

19.6 J

Explanation:

From conservation of energy,

`("K.E.")_"bottom" = ("K.E.")_"top" + ("P.E.")_"top"`

`therefore 1/2  "mv"_1^2 = 1/2  "mv"_2^2 + "mg" (2"r")`

`therefore "Change in K.E. is,"`

`therefore 1/2  "mv"_1^2 - 1/2  "mv"_2^2 = "mg" (2"r")`

`= 0.5 xx 9.8 xx 2 xx 2`

` = 19.6  "J"`