1 Robots with telescoping arms are sometimes used to perform tasks(e. g., welding or placing screws) where access may be difficult forother robotic types. During a test run, a robot arm is programmedto extend according to the relationship r = 3 + 0.5 cos(4θ) and thearm rotates according to the relationship θ = −π__4t2 + πt, where r isin feet, θ is in radians, and t is in seconds. Determine (a) the velocityand acceleration of the robot tip A at t = 3 s and

If steel is more dense that lake water, why can a boat float

Two point charges are on the y axis. a 3.90-µc charge is located at y = 1.25 cm, and a -2.4-µc charge is located at y = −1.80 cm. (a) find the total electric potential at the origin. v (b) find the total electric potential at the point whose coordinates are (1.50 cm, 0). v

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?