If a steel, thin-shelled wheel of radius r and mass M is moving along the road at 2 m/s, what is the total kinetic energy?

1) 2M

2) 3M

3) 1M

4) 5M

5) 4M

The moment of inertia for rolling motion is

I = Mr²

The linear velocity is v = 2 m/s. The rotational velocity is

ω = 2/r

The total KE (kinetic energy) is

KE = (1/2) Mv² + (1/2) I ω²

= (1/2) (M) (4) + (1/2) (Mr²) (4/r²)

= 2M + 2M

= 4M

Answer: 4M