Question

If the momentum of the body increases by 20% what will be the increase in the K.E. of the body? [3]

Answer 1

E=1/2(m)(v²)---------(i)
m-mass of object
v-velocity
E- kinetic energy

also, p=mv ---------(ii)
p-momentum

now, squaring both sides of (ii)
p²=m²v²

v²=p²/m²----------(iii)

put (iii) in (i)

E=1/2 m{p²/m²}

E=p²/2m------(A)

a/q
p is increased by 20%
so
p'= p+20p/100
p'=6p/5 ------ (B)

put p' in place of p in (A)

E'=(6p/5)² ÷2m

E'= 36 p²/25 ÷ 2m

E'= 36× E