Given, height of plane =28m angle of inclination, θ=30∘ By conservation of energy, Potential energy lost by the solid sphere in rolling down the inclined plane = kinetic energy gain by the sphere mgh‌=‌
1
2
mv2+‌
1
2
Iω2 ‌=‌
1
2
mv2+‌
1
5
mv2 mgh‌=‌
7
10
mv2 v2‌=‌
10
7
gh=√‌
10
7
×10×28 v‌=20m∕s The velocity of the sphere, when it reaches the bottom of the plane is 20m∕s.
