Question

abdul is pushing his 20. kg little brother on a merry go round with a radius of 2.0m. If his little brother is on the edge of the merry go round and has a angular momentum of 360 kg m^2sec. what is his speed?

Answer 1

Answer:

9.0 ms⁻¹

Explanation:

Thinking process:

First, we gather data:

mass = 20 kg

radius = 2.0 m

Angular momentum = 360 kgm²s

• Solving:

We know that:

momentum = $mr^{2}$

                   = (20) * (2)²

                   = 80 kgms²

Angular speed  = $\frac{360}{80}$

                          = 4.5 rads⁻¹

The tangential speed is given by the following equation:

tangential speed = angular speed * radius

                            $4.5 rads^{-1} * (2)\\ = 9ms^{-1}$

The speed is therefore 9 ms⁻¹

Answer 2

Angular momentum = inertia x rad/s = kg-m^2/s 

Inertia of little brother = mr^2 = 20 x 2^2 = 80 kg-m^2 

360 = 80 x rad/s 

360/80 = 4.5 rad/s (angular speed) probably the answer they are looking for. 

tangential speed = rad/s x radius = 4.5 x 2 = 9 m/s