A propeller, initially at rest, rotates about its midpoint with an angular acceleration of 12 rad/sec2. How much time will it take to rotate through a 90 deg angle?

What happens to light waves from a star as the star moves away from earth?

Atotal charge of –6.50 µc is uniformly distributed within a sphere that has a radius of 0.150 m. what is the magnitude and direction of the electric field at 0.300 m from the surface of the sphere? a) 2.89 × 105 n/c, radially inward b) 6.49 × 105 n/c, radially outward c) 4.69 × 105 n/c, radially inward d) 9.38 × 105 n/c, radially outward e) 1.30 × 106 n/c, radially inward

What is the equation for electrical work?