Who was the first to hypothesize that electron orbit a positively charged nucleus

In a closed system, the total energy prior to an energy transformation is the total energy after. a. equal to b. unrelated to c. greater than d. less than

Each line (unit) on the horizontal axis represents: 5 years 10 years 20 years all of the above

Orque can be calculated by multiplying the force (n) applied at 90∘ to the lever arm at a distance (m) from the pivot point (point of rotation), the compound si unit for the torque is n⋅m. if the force (at 90∘ to the lever arm) applied is 15 n and it is applied at 2.0 m from the pivot point (point of rotation), what is the torque on the lever?