The magnetic field b at the center of a circular coil of wire carrying a current i (as in fig. 20–9) is:
b = u0*ni/ 2r
where n is the number of loops in the coil and r is its radius. imagine a simple model in which the earth’s magnetic field of about 1g= (1 * 10 ^-4 t) near the poles is produced by a single current loop around the equator. roughly estimate the current this loop would carry.

Astudent throws a water balloon with speed v0 from a height h = 1.76 m at an angle θ = 21° above the horizontal toward a target on the ground. the target is located a horizontal distance d = 9.5 m from the student’s feet. assume that the balloon moves without air resistance. use a cartesian coordinate system with the origin at the balloon's initial position. (a) what is the position vector, rtarge t, that originates from the balloon's original position and terminates at the target? put this in terms of h and d, and represent it as a vector using i and j. (b) in terms of the variables in the problem, determine the time, t, after the launch it takes the balloon to reach the target. your answer should not include h. (c) create an expression for the balloon's vertical position as a function of time, y(t), in terms of t, vo, g, and θ. (d) determine the magnitude of the balloon's initial velocity, v0, in meters per second, by eliminating t from the previous two expressions.

The motion of water in a dam serves human beings by generating electricity as it is a controlled motion. give one example for an uncontrolled motion. what effects could it cause

What are the differences and relationships between speed, velocity, and acceleration