Answer:
Explanation:
False
When two waves overlap or superimpose over each other then they either undergo Constructive or destructive interference.
waves are the disturbance created by a force and add up to gives constructive interference when they are in the same line i.e. in the same phase.
When these disturbances are in the opposite phase then they superimpose to give destructive interference where the amplitude of the resulting wave will be much smaller as compared to original waves.
Answer: 
Explanation:
Given
Distance between two speakers is 8 m
Man is standing 12 away from the wall
When the person moves 3 parallel to the wall
the parallel distances from the speaker become 4+3, 4-3
Now, the difference of distances from the speaker is

Condition for destructive interference is

for second destructive interference; n=2

We have to covert 512 cal of heat in kilo joules.
As, 1 cal = 0.004184 kJ = 4.184 joules.
Therefore,

Thus, combustion of a small wooden match produces approximately ( in kilo joules ) is 2.142 kJ .
1.) Have your keys in hand before approaching or entering your car.
2. Be alert to other pedestrians and drivers.
3.) Search for signs of movement between, beneath and around objects to both sides of your vehicle
4.) check the spare tire for proper inflation