Question

If kinetic energy of a body is increased by 20% what will be the increase in its linear momentum?

Answer 1

The answer is
44
%
Method
If Momentum of the body increases by
20
%
it means that
Δ
P
=
20
%
of
P
before
=
0.2
P
before
=
0.2
m
u
⇒
Δ
P
=
0.2
m
u
where
Δ
P
is the increase in momentum
m
is mass
u
is initial velocity
v
is final velocity
⇒
m
v
−
m
u
=
0.2
m
u
Simplify that and you'll get,
v
=
1.2
u
We were asked to find the percentage increase in
K
E
,
Δ
K
E
=
x
K
E
before
And we're looking for that
x
⇒
x
=
Δ
K
E
K
E
before
⇒
x
=
1
2
m
v
2
−
1
2
m
u
2
1
2
m
u
2
=
1
2
m
(
v
2
−
u
2
)
1
2
m
u
2
=
v
2
−
u
2
u
2
Remember
v
=
1.2
u
⇒
x
=
(
1.2
u
)
2
−
u
2
u
2
=
0.44
u
2
u
2
=
0.44
x
=
44
%