37. What is the average (RMS) speed of a helium atom (He) in a helium baloon at room temperature (take the
mass of the helium to be 6.6 x 10-27kg) (A) 1.35km/s
(B) 1.36km/s (C) 1.37km/s (D) 1.36km/s (E)
None of the above​

he made 11 calls in one day

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

according to jean piaget, in what stage of cognitive development are children able to understand conservation task?

b. preoperational

just took it