Answer:
A) 5m/s
Explanation:
Momentum of ball in one direction=momentum of cannon in other direction
mv = mv
(10)(500)=(1000)v
5000=1000v
∴v=5m/s
I think it occurs whenever waves come together so that they are in phase with each other.
Answer:

Explanation:
Let say the empty wagon has mass "M"
now by newton's II Law we will have

now it is given that empty wagon is pulled with acceleration 1.4 m/s/s
now we will have

now a child of mass three times the mass of wagon is sitting on the empty wagon
so here we have


so we have

Answer:
71.4583 Hz
67.9064 N
Explanation:
L = Length of tube = 1.2 m
l = Length of wire = 0.35 m
m = Mass of wire = 9.5 g
v = Speed of sound in air = 343 m/s
The fundamental frequency of the tube (closed at one end) is given by

The fundamental frequency of the wire and tube is equal so he fundamental frequency of the wire is 71.4583 Hz
The linear density of the wire is

The fundamental frequency of the wire is given by

The tension in the wire is 67.9064 N
1.5 / 0.5 = 3 I believe this is the right answer