Question

friction. a 55 - kg box rests on a horizontal surface. the coefficient of static friction between the box and the surface is 0.30, and the coefficient of kinetic friction is 0.20. what horizontal force must be applied to the box to cause it to start sliding along the surface? express your answer with the appropriate units.

Explanation:

Step1: 计算物体重力

物体重力 \(G = mg\)，其中 \(m = 55\mathrm{kg}\)，\(g = 9.8\mathrm{m/s^2}\)，则 \(G=55\times9.8 = 539\mathrm{N}\)。

Step2: 计算最大静摩擦力

最大静摩擦力 \(f_{s,\text{max}}=\mu_s N\)，在水平面上 \(N = G\)，\(\mu_s=0.30\)，所以 \(f_{s,\text{max}}=0.30\times539\)。

Answer:

\(161.7\mathrm{N}\)