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A 1.2-kg mass is projected from ground level with a velocity of 31.3 m/s at some unknown angle above the horizontal. A short time after being projected, the mass barely clears a 16-m tall fence. Disregard air resistance and assume the ground is level. What is the kinetic energy of the mass as it clears the fence

Answer :

Cricetus

Answer:

The kinetic energy will be "399.65 J".

Explanation:

Given:

Mass,

m = 1.2 kg

Velocity,

v = 31.3 m/s

The total energy of mass will be:

⇒ [tex]E=K+U[/tex]

or,

⇒ [tex]E=.5mv^2+mgh[/tex]

By putting the values, we get

        [tex]=.5(1.2)(31.3)^2+0[/tex]

        [tex]=0.6\times 979.69+0[/tex]

        [tex]=587.81 \ J[/tex]

Since,

The system's total energy is unchanged, then

⇒ [tex]E=K+U[/tex]

or,

⇒ [tex]E=K+mgh[/tex]

   [tex]587.81=K+1.2(9.8)(16)[/tex]

   [tex]587.81=K+188.16[/tex]

          [tex]K=587.81-188.16[/tex]                

               [tex]=399.65 \ J[/tex]

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