Answer
given,
Weight of the child = 110 N
length of the swing,L = 2 m
now, calculating the potential energy when the string is horizontal
Potential energy = m g h
now, h = L (1 - cos θ) where θ is the angle made by the string with the vertical.
PE = m g L (1 - cos θ)
when rope is horizontal θ = 90°
PE = 110 x 2 (1 - cos 90°)
PE = 220 J
now, calculating potential energy when string made 25° with horizontal
PE = m g L (1 - cos θ)
when rope is horizontal θ = 25°
PE = 110 x 2 (1 - cos 25°)
PE = 20.61 J
The object's mass is irrelevant.
The acceleration due to Earth's gravity is inversely proportional to the square of the object's distance from the center of the Earth.
<h2>Answer: remain stationary</h2>
Stationary waves (so called because they seem to be immobile) occur when two waves interfere with the <u>same frequency, amplitude but with different direction</u>, along a line with a phase difference of half wavelength.
In this kind of waves there are two types of points:
The nodes, which are points that remain motionless or stationary and do not vibrate. They are due to the destructive interference of both waves when they meet.
The antinodes, which are points that vibrate with a maximum vibration amplitude. They are due to the non-destructive interference of both waves.
According to this explanation and comparing it with the description, when this two waves pass through each other, the point P will become a node, hence<u> it will remain stationary</u>.
