[单选题]
A box of mass 3kg is p
h56nd1f (o) brj+l ww1y.whlml
+l0mbb3cp4 x+(e fdja (/js ktaced on a box of mass 7kg. The coefficient of static friction between the surfaces of the boxes is 0.5. A horizontal forceF is applied to the 7kg box which sits on a
f(tpcx3dk(ja jbs b +e4 +lm0/frictionless surface.
What is the maximum value of F that can move the boxes without the 3kg box slipping?
A. 0.1g
B. 0.5g
C. 1g
D. 5g
参考答案:
D
本题详细解析:
Explanation:
The free-body diagrams of the boxes:
The maximum value of the force of friction Ff can be calculated as follows;
- Ff=μsFN=μsmg=(0.5)(3)g=1.5g
When Newton's Second Law is applied to the mass of 3kg;
Fnet=ma
1.5g=3a
0.5g=a
To move without slipping, both of the masses must have the same acceleration. Treating both boxes as one system
Hence, the correct answer is D.