Physics help question 4?

A building under construction requires building materials to be raised to the upper floors by cranes or elevators. An amount of cement is lifted 86.3 m by a crane, which exerts a force on the cement that is slightly larger than the weight of the cement. If the network done on the cement is 1.89 X 103 J, what is the magnitude of the net force exerted on the cement?

2 Answers
Dwight
Feb 5, 2018

The force on the cement must have been 21.9 N

Explanation:

The relation between work done, force exerted and displacement is

#W=F*d#

so, the force exerted to do the work must be

#F=W/d = (1.89xx10^3J)/86.3 m = 21.9 N

SCooke
Feb 5, 2018

Force = #21.9 N#

Explanation:

Force = #21.9 N#
We’re essentially looking at the energy input required to equal a potential energy difference of 86.3m. The SI unit of work is the joule (J), dimensionally: #1 kg*m^2/s^2#.
Work = Force x Distance
Force = #(1.89 xx 10^3)/86.3 = 21.9 N#

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