An inventive child wants to reach an apple in a tree without climbing the tree. Sitting in a chair connected to a rope that passes over a frictionless pulley (Fig. P4.79), the child pulls on the loose end of the rope with such a force that the spring scale reads 350 N. The child's true weight is 310 N, and the chair weighs 160 N.
(a) Show that the acceleration of the child-chair system is upward and find its magnitude.
(b) Find the force the child exerts on the seat of the chair.
The Attempt at a Solution
I solved for Part A and got it correct by going:
a=4.7956 which I rounded to 4.8 m/s^2
I'm having trouble with Part B. Here is the work I did so far:
350-120 N = 230 N
However, this is wrong and I'm not sure where I went wrong. If someone could help me, I'd be very thankful.