Answer:
Explanation:
Given
Distance between two loud speakers 
Distance of person from one speaker 
Distance of person from second speaker 
Path difference between the waves is given by

for destructive interference m=0 I.e.




frequency is given by

where 

For next frequency which will cause destructive interference is
i.e.
and 


frequency corresponding to this is

for 


Frequency corresponding to this wavelength

It's true, when we lift an object we add energy to it.
because, when we lift an object by applying force , the object attains a height and hence the energy gets stored in it, in the form gravitational potential energy .
The answer is 1.33 i hope this helps you
Answer: wave
Explanation:
These are the basic definitions and characteristic of the terms given, which show tha the only rigth answer is the second option: wave.
1) Force is an interaction. There are four natural forces: electrostatic, gravity, strong nuclear force and weak nuclear force.
2) Wave: is a sequence of pulses or vibrations that cause the continuous transportation of energy (propagation). There is not transport of mass, only energy.
Some examples of waves are sound waves, electromagnetic waves (light, radio waves, micro waves, infrarred waves, ultraviolet waves).
3) Vacuum: is the absence of matter; empty space. Only electromagnetic waves can travel through vacuum; other waves need a medium to travel.
4) Medium: any matter is a medium: a solid, the air, a liquid, all of them are media through which waves can transport its energy, depending of the wavelength.