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# Calculate the upthrust on an object of volume 50cm3 which is immersed in liquid ...

### Question

Calculate the upthrust on an object of volume 50cm3 which is immersed in liquid of density 103kgm-3 [g = 10ms-2]

A)
0.8N
B)
2.5N
C)
0.5N
D)
1.0N

### Explanation:

Upthrust = change in weight

density = $$\frac{\text{mass}}{\text{volume}}$$

Mass of liquid displaced = Density of Liquid × Volume;

= 103 × 50 × 10− 6m3

= 0.05kg

(Note that the volume of 50cm3 was converted to m3 by multiplying by 106) i.e 50cm3 = 50 × 10−6m3)

Since mass displaced = 0.05kg

Upthrust = mg = 0.05 × 10

= 0.5N

## Dicussion (1)

• Upthrust = change in weight

density = $$\frac{\text{mass}}{\text{volume}}$$

Mass of liquid displaced = Density of Liquid × Volume;

= 103 × 50 × 10− 6m3

= 0.05kg

(Note that the volume of 50cm3 was converted to m3 by multiplying by 106) i.e 50cm3 = 50 × 10−6m3)

Since mass displaced = 0.05kg

Upthrust = mg = 0.05 × 10

= 0.5N