# An object of mass 40kg is raised to a height of 5m above the ground.What is its PE?If the object is allowed to fall,find its KE when it is half way down An object of mass 40 kg is raised to a height of 5m above the ground.What is its PE?If the object is allowed to fall,find its KE when it is half way down

U = mgh = 40 x 5 x 9.8 = 4 x 5 x 98 = 20 x 98 = 1960 J

v2= u2 + 2gh = 0 + 2 x 2.5  x 9.8 = v2 = 49

= K = 1/2 mv2 = 1/2 x 40 x49 = 20 x 49 = 980 J

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mass , m = 40 kg
g = 10 m/s2
h = 5 m
P.E = mgh = 40 x 10 x 5 = 2000 J
K.E half way down = 1/2 of P.E
Total energy = P.E+K.E
K.E = 1/2 x 2000 = 1000 J

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Potential Energy (U)= mgh
= 40 x 5 x 9.8 Joules(J)
= 1960 J

(v)sqaure-(u)square =2gh   (g=9.8 m/(s)square)
(v)square-2=2 x 9.8 x 5
v = 10 m/(s)

Kinetic Energy (E) = 1/2 m(v)square
=  1/2 x 40  x 100 J
=  2000 J
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Which is write can anyone tell
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mass of an object=80 kg
height of an object=10 m
potential energy= mgh =80^10^10^
=8000J
kinetic energy when it is half way down
kinetic energy=1/2^m^v2
=1/2^80^(10/2)2^(10/2)2
=1000J

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