An 19.2-cm-long bicycle crank arm, with a pedal at one end is attached to a 21.7-cm-diameter sprocket, the toothed disk around which the chain moves. A cyclist riding this bike increases her pedaling rate from 58 rpm to 87 rpm in 9.4 s. What is the tangential acceleration of the pedal

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

at right angles to each other

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

b. preoperational

just took it