# 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?)