Question

how much a body of weight 35 N will weight in water if it displaces one litre of water?

Answer 1

weight of body = 35N
Body displaces one litre of water .
∵ Archimedes theory ,
weight of body in water = weigh of body in air - weight of water displaced by body

∵ 1 litre of water is displaced by body
∴ volume of water = 1 L
we know, density of water = 1000 kg/m³
Hence, mass of water = 1L × 1000 kg/m³
= 10⁻³ × 1000 kg [ ∵ 1L = 10⁻³ m³ ]
= 1kg

Now, weight of body in water = 35N - 1kg × 9.8 m/s² [ ∵ weight = mass × g]
= 35 N - 9.8N = 25.2N