# Three blocks with masses m 2m and 3m Answer with Explanation

Three blocks with masses m 2m and 3m are connected by strings, as shown in the figure. After an upward force F is applied on block m, the masses move upward at constant speed v. What is the net force on the block of mass 2m?

We have also provided an explanation for the answer.

## Three blocks with masses m 2m and 3m question

Question: Three blocks with masses m 2m and 3m are connected by strings, as shown in the figure. After an upward force F is applied on block m, the masses move upward at constant speed v. What is the net force on the block of mass 2m?

1.  4 mg
2.  2 mg
3.  0 mg
4.  1 mg

The correct option is 3 i.e 0 mg. The Explanation of the answer is as follows.

Consider the above diagram

Force F is applied to the three blocks and the blocks move at a constant speed v. Let us assume that tension in the first string is F1 and tension in the second string is F2

Since the block with mass 2m is moving at constant speed means the acceleration is zero. Hence: Hence, the net force on block of mass 2m is zero