A child stands on a horizontal rotating platform that is moving at constant angular speed. Thecentripetal force on the child is provided byA. the gravitational force on the child.B. the friction on the child’s feet.C. the tension in the child’s muscles.D. the normal reaction of the platform on the child.– 10 –2221 – 6510

A boy stands at the edge of a rotating table. In order to keep him movingin a circular path the table applies a certain force on the boy. Which of thefollowing is the reaction force to this force?A. The normal force on the boyB. The force of gravity exerted on the boy by EarthC. The force of gravity exerted on Earth by the boyD. The force exerted on the table by the boy that is directed straight downE. The static friction force exerted by the boy on the ta

A man stands on a platform that is rotating (without friction) with an angular speed of 0.9 rev/s. His arms are outstretched and he holds a weight in each hand. The rotational inertia of the system of man, weights, and platform about the central axis is 4.0 kg·m2. Assume that by moving the weights the man decreases the rotational inertia of the system to 2.0 kg·m2.(a) What is the resulting angular speed of the platform?

A 42.0-kg child takes a ride on a Ferris wheel that rotates four times each minute and has a diameter of 22.0 m.(a) What is the centripetal acceleration of the child?magnitude      m/s2direction      (b) What force (magnitude and direction) does the seat exert on the child at the lowest point of the ride?magnitude      Ndirection      (c) What force does the seat exert on the child at the highest point of the ride?magnitude      Ndirection      (d) What force does the seat exert on the child when the child is halfway between the top and bottom? (Assume the Ferris wheel is rotating clockwise and the child is moving upward.)magnitude      Ndirection      ° counter-clockwise from the horizontal

Suppose two children push horizontally, but in exactly opposite directions, on wagon with another child inside of it. The first child exerts a force of 75.0 N, the second child exerts a force of 90.0 N in the opposite direction, and 15.0 N of friction acts on the wagon. The mass of the third child plus wagon is 23.0 kg.Consider the system of interest if the acceleration of the child in the wagon is to be calculated. Draw a free-body diagram, including all forces acting on the system. Calculate the acceleration of the system.Group of answer choicesa = 6.5 m/s2a = 1.3 m/s2a = 0.65 m/s2a = 0 m/s2

8 A child of mass 20 kg stands on the rough surface of a sledge of mass 40 kg. The sledge canslide on a horizontal frictionless surface.One end of a rope is attached to the sledge. The rope passes around a fixed frictionless pole,and the other end of the rope is held by the child, as shown.horizontal rope frictionlesspolefrictionless surfaceThe rope is horizontal. The child pulls on the rope with a horizontal force of 12 N. This causes thechild and the sledge to move with equal acceleration towards the pole.What is the frictional force between the child and the sledge?A 4.0 N B 6.0 N C 8.0 N D 12 N