imported>Patrick at 14:50, 12 May 2011

2011-05-12T14:50:47Z

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The diagram shows all the forces acting on the mass and draws its free-body diagram. The x-axis is chosen in the direction of the slope. The acceleration is zero. 
[[image:N_APP_EX_21_SOLN.png|TOP]] 

Compute the components of all forces acting on the block:

{| border="1" cellpadding="2" style="text-align:center"
|-
! Forces
! x-component
! y-component
|-
! <math>F_S</math>
| <math>kx</math>
| 0
|-
! <math>F_N</math>
| 0
| <math>F_N</math>
|-
! <math>F_G</math>
| 20 cos(-127°)
| 20 sin(-127°)
|-
| <math>\Sigma F</math>
| 0
| 0
|}
 
Write equations and solve: In this case we are only interested in the x-component.

<math>kx - 20 \cos(-127^{\circ}) = 0</math>
<math>kx = 12</math>
<math>k = {12 \over x}</math>
<math>k = {12 N \over 1.5 \times 10^{-2} m}</math>
<math>k = 8 \times 10^2 N/m</math>

Newtons Laws EX 21 - Revision history

imported>Patrick at 14:50, 12 May 2011