A loaded ski lift pulls 20 chairs with people sitting in them up 200 meters. Each chair with a person has 250 kg of total mass. How much work does it take to lift them?

1 Answer
Nam D. · Steve J.
Jun 2, 2018

#9.8*10^6# joules

Explanation:

Since the ski pulls up the chairs in the #uarr^+# direction, we can assume that the total work done is the gain of gravitational potential energy of the chairs.

Gravitational potential energy is given by the equation:

#"GPE"=mgh#

where:

  • #m# is the mass of substance in kilograms

  • #g# is the gravitational acceleration, which is #9.8 \ "m/s"^2# on Earth

  • #h# is the height risen in meters

So, we get:

#W="GPE"=(250\ kg)/cancel("chair")*20\cancel("chairs")*9.8 \ "m/s"^2*200 \ "m"#

#=9800000 \ "kg m"^2"/s"^2#

#=9.8*10^6 \ "J" \ (because 1 \ "J"=1 \ "kg m"^2"/s"^2)#

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