Manipal Entrance Test 2013 Physics Paper

The kinetic energy of moving body is equal to half the product of the mass (m) of the body and the square of its speed (v‌2)
kinetic energy =

1

2

× mass ×(speed)2
i.e., =

1

2

mv2
Let mass of man is Mkg and speed is v and speed ofbody is v1 then

1

2

Mv2=

1

2

{

1

2

M

2

v12} ......(i)
when man speed up by 1 m/s,
v=v+1
∴

1

2

M(v+1)2=

1

2

{

M

2

}.v12 .....(ii)
Dividing Eqs. (i) by (ii), we get

v2

(v+1)2

=

1

2

√2v=v+1
v=

1

√2−1

m∕s