一道英文物理题

A 4kg body is placed on horizontal ground. The coefficient of dynamic friction between the body and the ground is 0,2. The object is acted upon by a force of 30 N that encloses an angles of 20 whith horizontal. Find the friction force and the acceleration of the body.

翻译:一个4kg的物体放置在水平面上.物体和地面之间的摩擦因数是0.2.物体受一个与水平面夹角是20度的力的作用,力大小是30N.求摩擦力和物体的加速度.

解答:竖直方向上物体没有加速度,受力平衡:
Fsin20度+N=mg 其中,F是拉力,N是支持力,令g=9.8m/s^2
f=μN f是摩擦力, 解出:f=μ(mg-Fsin20度)=5.83N
水平方向上有加速度a.则根据牛顿第二定律:Fcos20度-f=ma
解出:a=5.59m/s^2

In the vertical direction, the body doesn't have acceleration:
Fsin20+N=mg,
F is the force that act upon the body, N is the force of support from the ground. Let g be g=9.8m/s^2
f=μN,
f is the friction force, μ is the coefficient of dynamic friction between the body and the ground.
So, f=5.83N
In the horizontal direction, according to Newton's Second Law: (Fcos20-f)=ma
a is the acceleration.
So, a=5.59m/s^2

困难大概在翻译上吧。题目倒不难。
水平地面上放着一件4kg的物体，物体和地面之间的动摩擦系数为0.2，有一大小为30N，与水平线夹角20度的力作用在物体上。求摩擦力和物体加速度。
很简单的题，自己算算看吧。有问题我明天来看，实在太困。

楼上的翻译的已经很准确了
题目也应该不难的.

frictional force
0.2*(4*9.8-30*Sin20)
= 5.8 N

acceleration