Question

Three blocks with masses m, 3m and 6m 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 3 m? (g is the acceleration due to gravity)

Options

• zero

• 2 mg

• 3 mg

• 6 mg

Answer 1

zero

Explanation:

Since all three blocks are moving up with a constant speed v, acceleration a is zero.

⇒ F = 0

∴ Net force is zero.