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An object is thrown vertically upwards with velocity of 20ms^(-1). At what height will its kinetic energy and potential energy be equal? (g=10ms^(-2))

Answer»

`10m`
`20m`
`15m`
`5m`

Solution :`u=20ms^(-1)`
As per the law of CONSERVATION of MECHANICAL energy,
`(("Mechanical"),("energy of the"),("OBJECT on ground"))=(("Mechanical energy"),("of the object at"),("maximum height"))`
`therefore E_(k_(1))+E_(p_(1))=E_(k_(2))+E_(p_(2))`
`therefore (1)/(2)m u^(2)+0=0+mgh` (`because` Potential energy of the object on ground `E_(p_(1))=0` and kinetic energy of the object at the maximum height `E_(k_(2))=0`)
`therefore h=(u^(2))/(2g)=((20)^(2))/(2xx10)=20m`


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