Answer:

Explanation:
We know that speed is given by dividing distance by time or multiplying length and frequency. The speed of the father will be given by Lf where L is the length of the father’s leg ad f is the frequency.
We know that frequency of simple pendulum follows that 
Now, the speed of the father will be
while for the child the speed will be 
The ratio of the father’s speed to the child’s speed will be

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300 divide 1.5=200 let me know if this was helpful
Answer:
See below
Explanation:
Find the NET forces on the objects
A 20==>
B 0
C 30==>
D 15==>
So biggest accel = C because it has the most force acting on it
next is A because it has the next biggest force
next is D then B ...B has no net force acting on it