How much work is done by a person who picks up a 3-kg crate from the floor, raises it 2m and sends it flying with a speed of 4m/s

  82.8 J

Explanation:

The work done to raise the crate is ...

  PE = Mgh = (3 kg)(9.8 m/s^2)(2 m) = 58.8 J

The kinetic energy added to send the box flying is ...

  KE = (1/2)Mv^2 = (1/2)(3 kg)(4 m/s)^2 = 24 J

So, the total work involved in this activity is ...

  58.8 J +24 J = 82.8 J

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explanation:

coil wire, increase current, put iron inside the coil