Acomputer hard drive contains a circular disk with diameter 2.5 inches and spins at a rate of 7200 rpm (revolutions per minute). find the linear speed of a point on the edge of the disk in miles per hour.

Now to solve this problem, all we have to remember is the formula for calculating the linear speed given the radial speed, that is:

v = r w

where,

v = is the linear velocity or linear speed

r = is the radius of the circular disk = (1 / 2) diameter = (1/ 2) (2.5 inches) = 1.25 inches

w = is the radial velocity (must be in rad per time) = 7200 rev per minute

Calculating for v:

v = 1.25 inches (7200 rev per minute) (2 π rad / 1 rev)

v = 56,548.67 inches / minute

Converting to miles per hour:

v = 56,548.67 inches / minute (1 mile / 63360 inches) (60 min / hour)

v = 53.55 mile / hour

the arc length is found by finding the circumference of the full circle (2xpixradius) and then dividing by 4 to find just one quarter of the circle (90 degrees).

the answer to this is a. a^2 + b^2 = c^2