Joe is measuring the time it takes for a ball to roll down a ramp. in this experiment joe takes the measurement 5 times and gets the following results: 24.8, 23.9, 26.1, 25.1, 24.5 seconds. joe uses the standard deviation of these numbers as the "margin of error" on his measurement. does joe's average time agree with the accepted value of 25.9 seconds, within his margin of error? can anyone me with this?

Two identical 82 mg dust particles very far apart (pee 0) are moving directly toward each other at a speed of 3698 m/s. the charge on each is-719 ? c. determine how close they will get to each other. let k = 9x109 n-m2/c2 & ignore gravity.

On a horizontal frictionless surface, a small block with mass 0.200 kg has a collision with a block of mass 0.400 kg. immediately after the collision, the 0.200 kg block is moving at 12.0 m/s in the direction 30° north of east and the 0.400 kg block is moving at 11.2 m/s in the direction 53.1° south of east. use coordinates where the +x-axis is east and the +y-axis is north.(a) what is the total kinetic energy of the two blocks after the collision (in ) what is the x-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your ) what is the y-component of the total momentum of the two blocks after the collision? (indicate the direction with the sign of your answer.)

How many electrons does each element require in its valence shell to become stable?