Solid disk at rest starts to spin. The angular acceleration is constant. After 3 revolutions the wheel is spinning at 6radsec. Find the linear velocity andacceleration of a point on the disk 1.2 meters away from the center (axis) at20 seconds.

Explanation:

Given,

Angular displacement, θ = 3 rev

                                         = 3 x 2π = 6π

initial angular speed, ω = 0 rad/s

Angular speed when disk is revolved to 3 revolution = 6 rad/s

radius, r = 1.2 m

time, t = 20 s

Calculating angular acceleration

Acceleration of the disk

Now for linear velocity calculation

Linear velocity,

answer: option c. i.e. electric current flowing “downhill” from the negative electrode to the positive electrode in a battery

explanation:

the water analogy to the circuits define the pipes (water flows) to the electric current. now, we know that the electric current flows from the positive terminal to the circuit (as shown in the diagram attached).

hence, option c is the correct answer.