(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

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.

2. Relevant equations

F=ma

3. The attempt at a solution

I solved for Part A and got it correct by going:

700-470=47.96a

a=230/47.96

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:

310-350=-40

-40+160=120 N

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.

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# Force of child on a swing

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