Why spring balance measure weight not the mass of the body?​

The spring balance works on the principle which states that the weight of the body attached to the hook of the spring balance is directly proportional to the extension of the spring. Thus more the weight more the extension and less the weight, less is the extension. Due to this relation, the graduated scale of the spring balance is linear. Hope this helps you!

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27