Two blocks,B1 and B2 with masses of 12.0 kg and 5.60 kg,respectively,are in contact with each other on a frictionless horizontal surface.A purely horizontal force of 30.0 N is applied to B1,which in turn pushes B2 and both blocks accelerate together uniformly.The net horizontal force acting on B2 is
A)9.55 N.
B)15.0 N.
C)20.5 N.
D)30.0 N.
E)60.0 N.

Question

Quizplus · Accepted Answer

The net force acting on the system is 30.0 N, and it accelerates both blocks together. The acceleration of the system can be found using Newton's second law, $F = ma$, where $F$ is the total force applied, $m$ is the total mass, and $a$ is the acceleration. The total mass is $12.0 \, \text{kg} + 5.60 \, \text{kg} = 17.6 \, \text{kg}$. Thus, the acceleration $a$ of the system is $30.0 \, \text{N} / 17.6 \, \text{kg} = 1.7045 \, \text{m/s}^2$.The net force on B2 can be found by multiplying its mass by the acceleration of the system: $F = m \cdot a = 5.60 \, \text{kg} \cdot 1.7045 \, \text{m/s}^2 = 9.5452 \, \text{N}$, which rounds to $9.55 \, \text{N}$.

Two Blocks,B1 and B2 with Masses of 12