Explanation:
sinces : Momentum = velocity × mass
then : 30 = 10 × m and m = 30 ÷ 10 = 3 kg
Answer:
Incomplete question: The masses of the blocks m₂ = 1.5 kg and m₃ = 2 kg
Explanation:
Given data:
L₁ = length = 0.85 m
L₂ = 0.25 m
L₃ = 0.5 m
m₂ = 1.5 kg
m₃ = 2 kg
Question: Find the unknown mass of the block 1 needed to balance the bar, m₁ = ?
The torque is zero (intermediate point of the bar)

Is negative because mass 1 is to the left of the coordinate system (see the diagram)

The seat belt is applying a force in the opposite direction.