I got the following qn: In a circus performance, a large 5kg hoop of radius 3m rolls without slipping. If the hoop is given an angular speed of 3 rad/s while rolling on the horizontal and allowed to roll up a ramp inclined at 20 degrees with the horizontal, how far(measured along the incline) does the hoop roll? My solution is as follows: Total initial energy=0.5 * I * (angular velocity)^2 =0.5 * 45 * 3^2 =202.5 Final energy = mgh = 5gh, where h is the vertical height Equating the 2, 202.5=5gh h=4.128. Since we want to find the distance along the slope, d, d=h/sin20 = 12.1m This is the ans I got, but it seems that the back of the textbook ans is 24m . Is the textbook ans correct or wrong?