Help me with these please
_

The direction of the current in an alternating current circuit remains constant. is direct. changes repeatedly. changes randomly.

Ablock of mass m = 2.5 kg is attached to a spring with spring constant k = 740 n/m. it is initially at rest on an inclined plane that is at an angle of theta= 26 with respect to the horizontal, and the coefficient of kinetic friction between the block and the plane is uk = 0.17. in the initial position, where the spring is compressed by a distance of d = 0.16 m, the mass is at its lowest position and the spring is compressed the maximum amount. take the initial gravitational energy of the block as zero. the block's initial mechanical energy is 9.472 j.b. if the spring pushes the block up the incline, what distance l in meters will the block travel before coming to rest? the spring remains attached to both the block and the fixed wall throughout its motion.

Ajet plane flying 600 m/s experience an acceleration of 4.0 g when pulling out of a circular dive. what is the radius of curvature part of the path in which the plane is flying? a) 7100 m b) 650 m c) 9200 m d) 1200 m