Answer:
0.4 N
Explanation:
Draw a free body diagram of the block. There are three forces: weight force mg pulling down, buoyancy force ρVg pushing up, and tension force T pulling up.
Sum of forces in the y direction:
∑F = ma
T + ρVg − mg = 0
T = mg − ρVg
T = g (m − ρV)
Plugging in values:
T = (9.8 m/s) ((2.5 g/cm³ × 20 cm³) − (1 g/cm³) (10 cm³)) (1 kg / 1000 g)
T = 0.392 N
Rounded to one significant figure, the reading of the spring scale is 0.4 N.
