If F = 40 N and M = 1.5 kg,what is the tension in the string connecting M and 2M? Assume that all surfaces are frictionless.
A)13 N
B)23 N
C)36 N
D)15 N
E)28 N

Question

If F = 40 N and M = 1.5 kg,what is the tension in the string connecting M and 2M? Assume that all surfaces are frictionless. 
A)13 N 
B)23 N 
C)36 N 
D)15 N 
E)28 N

Quizplus · Accepted Answer

Since all surfaces are frictionless, the tension throughout the string is constant. Thus, we can consider the tension in the string connecting M and 2M as equal to the tension in the string connecting M and the wall. 
Using Newton's second law, F = ma, we can find the acceleration of the system.
F = T - Mg
where T is the tension in the string connecting M and the wall, and g is the acceleration due to gravity.

Substituting the values, we get:
40 = T - (1.5)(9.8)
T = 23 N

Hence, the tension in the string connecting M and 2M is also 23 N. 
Therefore, the best choice is B) 23 N.