Question

Un objeto tiene una masa de 35 kg y su energía mecánica inicial es de 102,000 J. Sube hasta llegar a su altura máxima. Suponga que perdió el 25% de su energía mecánica inicial debido a la resistencia del aire. Calcule que distancia subió.

Answer 1

Due to the presence of air which is a dissipative force, the total mechanical energy of the object is not conserved.

Thus. from the extension of the conservation of energy principle to non mechanical systems we must have

where W_a is the work done by the air.

The initial energy of the object is entirely kinetic while at the maximum height it is entirely potential.

i.e.K₁=102000 J, U₁=0 J,K₂=0J and U₂=mgh from the definition of potential energy.

On simplifying the above equation we obtain:

Now m=35 kg, g=9.8 m/s² so that we have:

This is the required answer.