a) 29,900 J
b) 13,800 Nm
Explanation:
a)
The work done by a force on an object is given by:
[tex]W=Fd[/tex]
where
F is the magnitude of the force
d is the displacement of the object
In this problem:
The force applied on the crate must be equal (at least) to the weight of the crate. Therefore, in this case,
F = W = 11,500 N
The distance through which the crate has been lifted is
d = 2.6 m
Therefore, the work done to lift the crate is:
[tex]W=(11500)(2.6)=29,900 J[/tex]
b)
Here we are said that the weight of the fork-lift truck and driver cause an anticlockwise moment.
When there is an unbalanced moment, the object starts to rotate around a certain pivotal point.
In this case, we want to find the minimum size of the anticlockwise moment needed in order for the fork-lift truck not to rotate.
In order for this to happen, the net overall moment on the truck must be zero: this means that the anticlockwise moment must be equal to the clockwise moment,
[tex]M_A=M_C[/tex]
In this case, the clockwise moment is
[tex]M_C=13,800 Nm[/tex]
Therefore, the anticlockwise moment must be equal:
[tex]M_A=13,800 Nm[/tex]
