To find change in PE, we have to consider only vertical motion of the ball. So, we have uy=24m∕s,m=1kg ay=−10m∕s2,t=6s We take origin at point of projection, h‌‌=uyt−‌
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gt2=24×6−‌
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×10×36 ‌‌=144−180=−36m So, vertical displacement of the particle is h=−36m Hence, change in PE=mgh=1×10×−36=−360J