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at a construction site a crane lifts a block of mass,m,vertically upwards through a height of 70 m at constant speed by means of a strong cable.The block experiences a force of magnitude 8 N as a result of air friction as it is lifted vertically upwards.
The cable does 377 860 J of work in moving the block through a height of 70 m.calculate the mass of the block.

  • science -

    work done=mass*g*height+frictionforce*height

    solve for mass.

  • science -

    should'nt i use the equetion mgh + half mv^2before=mgh + half mv^2aftr?

  • science -

    U=mgh

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