A 1 gram spiders sits on a platform rotating at 78 rpm. the spider is 15 cm from the centre disk. find the speed of the spider

The spider is traveling in a circle with radius = 15cm

The circumference of any circle = 2 pi (radius)

The circumference of the spider's path = 2 pi (15 cm) = 30 pi cm

The spider completes a trip around this path 78 times per minute.

Its speed, relative to you, is

(78) x (30 pi) cm/min =

2,340 pi cm/min = 7,351.33 cm/min =

73.5133 meter/min =

4.411 km/hr =

2.74 miles/hour

(After the last appearance of pi,

all numbers are rounded.)