How much work does it take to raise a #31 kg # weight #32 m #?

2 Answers
Mar 27, 2018

Consider the change is potential energy incurred as a result of raising the body of mass.

Recall,

#"PE" = mgH#

#W=F*d*costheta# where #costheta = 1# in this case,

due to the assumption of "horizontal" acceleration.

We can then say, #W = Delta"PE"#, and assume we move the body of mass from a height of #0m#

Hence,

#W = mgH - 0#
#=> W = 31"kg" * (9.8"m")/"s" * 32"m" approx 9.7*10^3"J"#

of work must be done on this body of mass to raise to the height you describe.

Mar 27, 2018

Answer:

I get #9721.6 \ "J"#.

Explanation:

Well, work is defined through the equation,

#W=F*d#

  • #F# is the force in newtons

  • #d# is the distance moved in meters

The force here is the weight of the box, which is given by,

#W=mg#

  • #m# is the mass of the object in kilograms

  • #g# is the gravitational acceleration in #"m/s"^2#, on Earth it's around #9.8 \ "m/s"^2#.

And so, the weight here is #31 \ "kg"*9.8 \ "m/s"^2=303.8 \ "N"#.

Therefore, the work done is:

#W=303.8 \ "N"*32 \ "m"#

#=9721.6 \ "J"#