Determine the kinetic energy of a body weighing 1 kg, thrown horizontally at a speed of 20 m / s

| May 8, 2021 | education

Determine the kinetic energy of a body weighing 1 kg, thrown horizontally at a speed of 20 m / s at the end of the fourth second of its flight.

m = 1 kg.

g = 10 m / s2.

V0 = 20 m / s.

t = 4 s.

Ek -?

The kinetic energy of the body Ek is determined by the formula: Ek = m * V ^ 2/2, where m is the mass of the body, V is the speed of its movement.

Horizontally, the body will move uniformly with a speed Vg = V0.

Will move vertically with free fall acceleration g and initial vertical velocity equal to the bullet. After time t, the body will have a vertical velocity component Vw = g * t.

By the Pythagorean theorem: V ^ 2 = Vg ^ 2 + Vv ^ 2 = V0 ^ 2 + g ^ 2 * t ^ 2.

Ek = m * (V0 ^ 2 + g ^ 2 * t ^ 2) / 2.

Ek = 1 kg * ((20 m / s) ^ 2 + (10 m / s2) ^ 2 * (4 s) ^ 2/2 = 2000 J.

Answer: the body will have kinetic energy Ek = 2000 J.



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