[单选题]
An object starts to move in a straight
xpylwln )8+ v: line
jl7 vdx*4ym3j under the effect of two opposite forces of 12N and 1
3v4l x*jmjd7y6N
After 5s, the displacement of the object is 25m. What is the mass of the object?
A. 1kg
B. 2kg
C. 3kg
D. 4kg
参考答案:
B
本题详细解析:
Explanation:
From the equations of motion, the following expression can be written:
The object starts to move from rest, therefore u=0:
By applying Newton’s Second Law to the object,
F16−12m=ma=(m)(2)=2 kg