Question

A boy of mass 18kg is running with a speed of 12km/h find the kinetic energy posssessed by the boy

Answer 1

Answer:

Speed, =12*5/18=10/3m/s

Mass=18kg

KE=1/2mv2=1/2*18*(10/3)^²=100J

Answer 2

Answer:

$\large\bold\red{100\:Joules}$

Explanation:

Given,

Mass of the Boy = 18 Kg

Also,

Speed of boy =$12\: Km{h}^{-1}$

Now,

we need to convert the speed into SI unit $m{s}^{-1}$

Therefore, to convert it,

we neet to multiply it with 5/18

Thus,

we get,

$speed = \frac{12 \times 5}{18} = \frac{10}{3} m {s}^{ - 1}$

Now,

we know that,

Kinetic Energy of a body having mass m and speed v is given by,

$\large \bold{\frac{1}{2} m {v}^{2}}$

Therefore,

putting the values,

we get,

$= > KE = \frac{1}{2} \times 18 \times { (\frac{10}{3}) }^{2} \\ \\ = 9 \times \frac{100}{9} \\ \\ = 100 \: joule$

Hence,

Kinetic Energy = 100 Joules