Question

Consider a father pushing a child on a playground merry 90 round. The system has a moment of inertia of 14.4 kgm its 1.50 m radius to achieve a torque of 375 N m . . The father exerts a force on the merry-go-round perpendicular to (a) Calculate the rotational Kinetic energy (in) in the merry-go-round plus child when they have an angular velocity of 14.8 rpm. (b) Using energy considerations, find the number of revolutions the father will have to push to achieve this angular velocity starting from rest. revolutions (c) Again, using energy considerations, calculate the force (in N) the father must exert to stop the merry-go-round in six revolutions.

Answer 1

1- 84.8 Kg ma r=1.5m r = 375 Nm ła tod 375 84% = 4.42 rad keel a) KELIW N = 14.8rpm Wa ZAN = 2KX 14.8 rad isec = 1.528 radio KE = 1 / 2 x 84.8x15282 = 99.115 Work done = K.E 7.0 = 99.11 3 0 - 99.11 - rad = 0.264 rad 0= 15.14 -0.04 rer 0 = 6x21 rad = 12k 375 sad = 20- 99.11 3 2 > 2.99.11 - - 2.628 121 Far = 2.628 F= 2.628 = 1.7520 いら