If a particle's position is given by x=4-12t+3t^2 (where t is in seconds and x is in meters), what is its velocity at t=1s? b. is it moving in the positive or negative direction of x just then? c. what is its speed just then? d. is the speed increasing or decreasing just then? e. is there ever an instant when the velocity is zero? f. is there a time after t=3s when the particle is moving in the negative direction of x?

Any color picture tube and electric field exerts a net force of magnitude 1.68x 10^-13 n on an electron the rest mass of an electron is 9.11 x 10^-13 what is the electron acceleration?

Samir watches a 100-minute movie on his spaceship. maria's spaceshipe flies in the same direction as samir's spaceship but she observes his move to last 125 minutes and his spaceship to be 40 m long. how long does samir observe his own spaceship to be? according to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does marias voyage take according to samir?

Acar travels in reverse. it covers 150 meters in 12 seconds what is the velocity of the car what is the speed of the car