The body has kinetic energy E = 100J and momentum P = 40kg * m / s. What is body weight?

For a closed system, the kinetic energy is equal to:
Ek = (m * V ^ 2) / 2, where Ek is the kinetic energy of the body (Ek = 100 J), m is the mass of the body (kg), V is the speed of the body (m / s).
Body momentum can be calculated using the formula:
P = m * V, where P is the body impulse (P = 40 kg * m / s).
Let us express the speed of the body:
V = P / m.
Ek = (m * V ^ 2) / 2 = (m * (P / m) ^ 2) / 2 = P ^ 2 / 2m.
Let’s express and calculate the body weight:
m = P ^ 2 / 2Ek = 40 ^ 2 / (2 * 100) = 8 kg.
Answer: Body weight is 8 kg.