Answer:
The constriction causes the mercury column to break under tension, leaving a vacuum between the bottom of the column and that in the bulb, and the top of the column stays still at the position reached in the body - a "peak hold" system.
When 2 waves interefere (or collide with eachother), it usually affects the crest of the wave. If both waves collide with both crests, it will create an amplified crest, and the waves will pass through eachother afterwards. If a trough of a wave meets a crest, it will cause the crest to be lowered shortly before both continue on.
1st derivative gives velocity;
d r(t)/ dt = 2t i + 6 j + 4/t k
2nd derivative gives acceleration;
d^2 r(t)/ dt^2 = 2 i - 4/ t^2
Speed ;
Square root of (4 t^2 + 36 + 16/ t^2)
For a given time, like 2 seconds, t will be 2. And answer of speed will be scalar.
