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In a shotput event, an athlete throws th...

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

A

2.5 J

B

5.0 J

C

52.5 J

D

155.0 J

Text Solution

Verified by Experts

The correct Answer is:
D
As air resistance is negligible, total mechanical energy of the system will remain constant.
Given, `h=1.5m`,`v=1(m)/(s)`,`m=10kg`,`g=10ms^-2`
From conservation of mechanical energy.
`(PE)i+(KE)i=(PE)f+(KE)f`
`impliesmgh+(1)/(2)mv^2=0+(KE)f`
`implies(KE)f=mgh+(1)/(2)mv^2`
`implies(KE)f=10xx10xx1.5+(1)/(2)xx10xx(1)^2`
`=150+5=155J`
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