Question

A beaker of water rests on an electronic balance that reads 995.0 g . A 2.3-cm-diameter solid copper ball attached to a string is submerged in the water, but does not touch the bottom.

Part A

What is the tension in the string? Express your answer using two significant figures.

Part B

What is the new balance reading?

Express your answer using five significant figures.

Answer 1

Solution:

Copper density: 8.96 g/cm³

Density = mass / volume

Volume = πd³/6

= 3.14 x (2.3)³/ 6

Volume = 6.373 cm³

Mass = density x volume

= 8.96 x 6.373

Mass = 57.10 gram

meanwhile, the sphere displaces 6.373 cm³ of water which has a mass of 6.373 grams.

so the copper losses an apparent mass of 6.373 grams. the scale must pick up the same amount.

T = (m-M) g

= ( 57.10 - 6.373 ) x 9.8 / 1000 { here we devide by 1000 to convert gram in to kilogram}

T = 497.1296 / 1000

T = 0.497 N

Part-B

New Scale Reading = W = 995 gram + 6.373 gram

= 1001.373 gram

W= 1.001373 kg { devide 1000 to convert in to gram }

New scale reading is 1.001373 kg