At what speed did a body weighing 1000 kg move if, when it was decelerated to a complete stop

At what speed did a body weighing 1000 kg move if, when it was decelerated to a complete stop, the friction force performed work equal in magnitude to 50 kJ?

Initial data: m (mass of a moving body) = 1000 kg; A (the work done by the friction force to stop the body) = 50 kJ = 50 * 10 ^ 3 J
The work done by the friction force to stop the body is equal to the change in its kinetic energy: A = ΔEk = Ek1 – 0 = m * V2 / 2, whence V = √ (2A / m).
Let’s do the calculation: V = √ (2 * 50 * 10 ^ 3/1000) = 10 m / s.
Answer: Before braking, the body was moving at a speed of 10 m / s.