Three blocks with masses m, 2 m and 3 m 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 2 m? (g is the acceleration due to gravity)

Three blocks with masses m, 2 m and 3 m 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 2 m? (g is the acceleration due to gravity) Correct Answer zero

CONCEPT:

• Force: It is any interaction that, when unopposed, will change the motion of an object.
  • A force can cause an object with mass to change its velocity, i.e., to accelerate.
  • Force can also be described intuitively as a push or a pull.
  • A force has both magnitude and direction, making it a vector quantity. 
  • S.I Unit is Newton.

Formula:

F = ma

where, m = mass, a = acceleration

EXPLANATION:

Given that, First mass = m, Second mass = 2m, Third mass = 3m, Constant speed = V,  force = f

The masses move upward at constant speed v.

Constant speed means,

dv/dt = 0

Acceleration = dv/dt = 0

Net acceleration is zero

Net acceleration is zero then the net force will be zero.

The net force on the block of mass 2 m

Using the formula of force,

F = ma = 2 × 0 = 0

Hence net force on the block is zero.