A box of mass 2.5 kg is lifted from the floor to a shelf 3.0 metres above the floor. How much work is done?

1 Answer

Answer:

#"75 J"#

Explanation:

  • Displacement #= \ "3 m"#
  • Mass #= \ "2.5 kg"#

#color(red)("Force" = "mass" xx "acceleration")#

The acceleration due to gravity #= "10 m/s"^2# (approx)

So

#"Force" = "2.5 kg" xx "10 m/s"^2 = "25 N"#

Now use

#"Work"# #"done" = "force" xx "displacement" xx cos theta#

Here

#theta = 0^@ => cos(theta) = 1#

So

#"work" = "25 N" xx "3.0 m" xx 1 = "75 J"#