Final answer:
The linear speed of the disc's edge is 1.13 meters per second.
Step-by-step explanation:
To solve this problem, we need to convert the 120 mm diameter of the disc to meters by dividing it by 1000 (since there are 1000 millimeters in a meter), which gives us a diameter of 0.12 meters. The linear speed of a point on the edge of the disc can be found using the formula V = ω × r, where V is the linear speed, ω is the angular velocity, and r is the radius of the disc. We can find the radius by dividing the diameter by 2, so the radius is 0.06 meters. We are given the angular velocity of 180 rpm, so we need to convert it to radians per second by multiplying it by 2π/60 (since there are 2π radians in one revolution and 60 seconds in one minute). This gives us an angular velocity of 18.8496 radians per second. Now we can substitute the values into the formula and calculate the linear speed:
V = 18.8496 radians/second × 0.06 meters = 1.13 meters/second