The arm of a crane at a construction site is 15.0 m long

  • Thread starter DrunkApple
  • Start date
  • #1
111
0

Homework Statement


The arm of a crane at a construction site is
15.0 m long, and it makes an angle of 15.8
with the horizontal. Assume that the max-
imum load the crane can handle is limited
by the amount of torque the load produces
around the base of the arm.
What maximum torque can the crane with-
stand if the maximum load the crane can
handle is 779 N?
Answer in units of N · m

Homework Equations


torque = rFsin θ

The Attempt at a Solution


torque = radius * Force of gravity * sin θ
= 15 m * 779 N * sin 15.8
I don't get what is wrong...
 

Answers and Replies

  • #2
Delphi51
Homework Helper
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"torque = 15 m * 779 N * sin 15.8"

Surely it should be cosine rather than sine?
 
  • #3
111
0


uhhh can i ask why it's cosine?
 
  • #4
Delphi51
Homework Helper
3,407
11


Torque is the vertical force times the horizontal distance from the pivot. The angle of the crane with horizontal is given. So 15*cos(15.8) is the horizontal component of the crane's length.
 

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