На плавление железного грузика ушло 54 000 Дж энергии, найдите массу грузика.

the answer is a 3.8cm

explanation:

real, smaller and upside-down.   so the answer should be b.

iron would move it is magnetic there is a mag field around the current in the wire

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me