A disc of radius 0.1 m rolls without sliding on a horizontal surface with a velocity of 6 m/s. It then ascends a smooth continuous track as shown in figure. The height up to which it will ascend is (x/5) m. Value of x is? (g = 10 m/s²)
Physics · Mixed Chapter
JEE Mains

Question

A disc of radius 0.1 m rolls without sliding on a horizontal surface with a velocity of 6 m/s. It then ascends a smooth continuous track as shown in figure. The height up to which it will ascend is (x/5) m. Value of x is? (g = 10 m/s²)

Physics · Mixed Chapter

G1 Physics · Accepted Answer

Step 1: On the smooth inclined track there is no tangential friction and hence no torque about the disc's centre; its rotational kinetic energy remains unchanged. Step 2: Only the translational kinetic energy is converted to gravitational potential energy: ½mv²=mgh. Step 3: h=6²/(2×10)=36/20=1.8 m=9/5 m. Therefore x=9.