The answer should be C) Slide against each other.
Answer:
I think its B
Explanation:
because "This means that when you rubbed the plastic comb along your hair, your hair resisted the movement of the comb and slowed it down. The friction between two surfaces can cause electrons to be transferred from one surface to the other."
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

Answer:
The answer to your question is: D.
Explanation:
Distance refers to the amount of space between two points, it is a scalar quantity.
Displacement refers to the space between two points, measure from the minimum path linking them, it is a vector quantity.
I'm not agree with these answers, because the total distance is approximately 500km.
A) The distance traveled is 300 km. This answer is not correct.
B) Distance is 300 km and displacement is 0 km. This answer is not correct because the displacement is also 500 km.
C) Distance is 300 km/hour and displacement is 300 km.
300 km/h is a measure of speed not of distance, this option is wrong.
D) Both distance traveled and displacement are 300 km. I think this is the correct answer because distance and displacement measure the same. but I think both measure 500 km.