you can check attachment for answer.
kind regards
One scientist proposes an idea and other scientists repeat his or her experiments so they can Accept the Idea.
maximum allowed value of the speed in roller coaster is given as

now from kinematics we can say

here initial speed will be

acceleration is due to gravity

now we can use this to find the height



so maximum allowed height will be 20.4 m
For balancing the lever, force on both the sides shall be equal. so,
Force on 3 m end = m × a = 3 × 98.1 = 294.3
Now, on 6 m end, it would be: = 294.3/6 = 49.05
After rounding-off to the nearest hundredth value, it would be: 49 N
Finally, Option A would be your correct answer.
Hope this helps!
Answer:
nodding of head ,yes- static equilibrium
nodding of head, no- dynamic equilibrium.
Explanation:
static equilibrium monitors head position when body is not moving .
dynamic equilibrium monitors the angular or rotational movements of the head when body moves.