A rock rotates around a light, 4-m long string. The rock is initially at rest, but reaches 150 RPM in 3 seconds. Calculate its tangential acceleration after 3 s. 
BONUS:Calculate its tangential speed after 3 s.

The time-dependent position of a point object which moves counterclockwise along the circumference of a circle (radius R) in the xy plane with constant speed υ is given by

r→ = î R cos ωt + ĵ R sin ωt

where the constant ω = v/R. Determine the velocity v→ and angular velocity ω→ of this object and then show that these three vectors obey the relation v→ = ω→ x r→ .

(II) The platter of the hard drive of a computer rotates at 7200 rpm (rpm = revolutions per minute = rev/min)

(b) If the reading head of the drive is located 3.00 cm from the rotation axis, what is the linear speed of the point on the platter just below it?

(II) The platter of the hard drive of a computer rotates at 7200 rpm (rpm = revolutions per minute = rev/min)

(c) If a single bit requires 0.50 μm of length along the direction of motion, how many bits per second can the writing head write when it is 3.00 cm from the axis?

A disc of radius 10 m rotates around itself with a constant 180 RPM. Calculate the linear speed at a point 7 m from the center of the disc.

A 4 m long blade initially at rest begins to spin with 3 rad/s² around its axis, which is located at the middle of the blade. It accelerates for 10 s. Find the tangential speed of a point at the tip of the blade 10 s after it starts rotating.