A body weighing 1 kg, thrown from a tower 7 m high at a speed of 8 m / s, fell on the Earth’s surface at a speed of 14 m / s

A body weighing 1 kg, thrown from a tower 7 m high at a speed of 8 m / s, fell on the Earth’s surface at a speed of 14 m / s, calculate the change in the total mechanical energy of the body at the moment of its fall on the Earth’s surface.

To find the losses of the total mechanical energy of a thrown body, we use the equality: Ep0 + Ek0 = Ek1 + A, whence we express: A = Ep0 + Ek0 – Ek1 = m * g * hb + m * Vn ^ 2/2 – m * Vk ^ 2 / 2 = m * (g * hb + Vn ^ 2/2 – Vk ^ 2/2).

Variables and constants: m – body weight (m = 1 kg); g – acceleration due to gravity (g ≈ 10 m / s2); hb – tower height (hb = 7 m); Vн – initial speed (Vн = 8 m / s); Vк – falling speed (Vк = 14 m / s).

Calculation: A = m * (g * hb + Vn ^ 2/2 – Vk ^ 2/2) = 1 * (10 * 7 + 8 ^ 2/2 – 14 ^ 2/2) = 4 J.

Answer: At the moment of the fall, the total mechanical energy decreased by 4 J. One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.