STIMULATING SLIPPAGE IN BALL BEARINGS BY INVESTIGATING THE CRITICAL ANGLE OF SLIPPAGE OF A SOLID SPHERE

Dissipative losses in ball bearings occur due to slippage in machine parts. This study examines how the slippage of a solid marble varies with its angle of inclination. During slippage, experimental linear velocity at the bottom of the ramp is greater than theory predicts. The ratio of translational/rotational KE, which theory predicts as 2.5, increases beyond θ_c, reaching (15.86 ± 0.68) for 75°

Photogates were placed at bottom of incline of length (0.575 ± 0.001) m. The linear velocity of a solid marble with mass (19.46 ± 0.001) g was measured in 8 trials for angles between 5-75°; µ_s between the marble and an acrylic incline was measured to be 0.264 ± 0.002. The critical angle, tan^-1 (7µ_s/2), was estimated at 42.7°± 0.3°.

The experimental velocity exceeded theory beyond error at 30°, invalidating our prediction of 42.7°. While the values for θ = 5° was accurate to 0.01 m/s, θ = 75° differed by 0.41 m/s. The ratio E_k/E_r was 2.5 only till 30°. The angular velocity peaked at 30° and rapidly fell beyond, because of slippage. To prove lack of friction caused slippage, the marble was replaced with  rubber ball with greater µ_s. Slippage occurred only beyond 60°.