Question
A 1-kg mass hangs by a string from a disk with radius 4.6 cm which has a rotational inertia of 5 × 10-5 kg·m2. After it falls a distance of 0.8 meters, how fast is it going to the nearest hundredth of a m/s?
Answers
bobpursley
change In PE=change in KE
mg*.8=1/2 m v^2 + 1/2 I w^2
but w=v/r
so w^2=v^2/r^2 and I= 1/2 m r^2
so
mg*.8=1/2 m v^2 + 1/4 mv^2
solve for v. Notice the mass m divides out.
mg*.8=1/2 m v^2 + 1/2 I w^2
but w=v/r
so w^2=v^2/r^2 and I= 1/2 m r^2
so
mg*.8=1/2 m v^2 + 1/4 mv^2
solve for v. Notice the mass m divides out.