Question

A 10cm×10cm×10cm block of steel ( rhosteel=7900kg/m3 ) is suspended from a spring scale. The scale is in newtons. (a) What is the scale reading if the block is in air? (b) What is the scale reading after the block has been lowered into a beaker of liquid with rho=700 kg/m3 and is completely submerged?

Answer 1

The scale reading when the block is in air is 7.84 x 10^5 N, and when it is completely submerged in the liquid, the scale reading is 6.86 x 10^5 N.

Step-by-step explanation:

(a) When the block of steel is in air, the scale reading will be equal to the weight of the block. The weight of the block (W) can be calculated using the formula W = m*g, where m is the mass of the block and g is the acceleration due to gravity (approximately 9.8 m/s^2). Therefore, the scale reading will be 10 cm x 10 cm x 10 cm x 7900 kg/m^3 x 9.8 m/s^2 = 7.84 x 10^5 N.

(b) When the block of steel is completely submerged in the liquid with a density of 700 kg/m^3, the scale reading will be equal to the buoyant force acting on the block. The buoyant force (Fb) can be calculated using the formula Fb = rho * V * g, where rho is the density of the liquid, V is the volume of the block, and g is the acceleration due to gravity. Therefore, the scale reading will be 10 cm x 10 cm x 10 cm x 700 kg/m^3 x 9.8 m/s^2 = 6.86 x 10^5 N.