Space Time & Motion A.2 Forces & Momentum (id: 973ec83ca)

本题目来源于试卷: Space Time & Motion A.2 Forces & Momentum，类别为 IB物理学

[单选题]
A block of mass 4.0 kg rests on an inclined plane.

The coefficient of static friction between the block and the plane $\mu_s$ is 0.4.
Which of the following gives the angle of inclination at which the block will start to slide?

• 
  

A. $\sin^{-1} (0.4)$
B. $\tan^{-1} (0.4)$
C. $\cos^{-1} (0.4)$
D. $\tan^{-1} (0.6)$


参考答案:  B


本题详细解析:

N=mg$\cos \theta$

F=$\mu_s$N

F=mg$\sin \theta$

mg($\sin \theta$)=0.4mg($\cos \theta$)

$\frac{sin \theta}{cos \theta}$=0.4

$\tan \theta$=0.4

$\theta$=$\tan ^-1$(0.4)

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