Phyics help

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I have a few physics questions:
1. How much mechanical work is done by a weightlifter holding a mass of 100 kg, 2.0m above the floor for 3.0 s? Explain ur answer.

2. Calculate the force needed to do 2.0 kJ of work to push a load of bricks 10m?

3. A carpenter applied a force of 60N horizontally to push a plane 40cm along a piece of wood, how much work does he do?

4. A librarian does 8.0J of work to stack five identical books on top of each other. If each book has a thickness of 4.0cm what is the mass of each book?

  • Phyics help -

    It appears you are posting several questions under different names. Sorry.

  • Phyics help -

    you don't understand i don't get this unit and i'm failling this unit miserabely really need help

  • Phyics help -

    Show your work. I will be happy to critique your work and thinking.

  • Phyics help -

    ok so here's how i thought i would have to solve these:
    1. W=mgh
    =100*9.8*2.0

    or w=0 because u lift the mass upards and carry it (perpenticular ) hence w=0

    2. W=f delta D
    W/D=Force

    3. W=60N * 40cm (ordo i convert 40 cm to kg)

    4. W=mgh
    W/h=m (do i convert 4.0 cm to kg?)

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