<span>since sound travels using mechanical waves and needs a material medium to propagate and since mechanical waves spread through vibrations ...and since hard materials have their atoms packed closely....they need to vibrate with a smaller amplitude to pass on the wave....thus sound travels faster in a denser medium than a less dense one.</span>
Answer:
a. Potential energy decreases and Kinetic energy increases
Explanation:
Because as he comes down due to its steepness the speed of the boy or you can say his KE increases and since he comes from a high position (hill) to the lower ground his potential energy decreases simultaneously
Answer:1.55 times
Explanation:
Given
First wavelength
Second wavelength
According wien's diplacement law
where 
T=Temperature
Let 
be the temperatures corresponding to 
respectively.
Thus object with 
is 1.55 times hotter than object with wavelength 
All it does is lets him pull in a more convenient direction to raise the load. It has no effect on the required force.
The correct answer should be bounced off since the light ray hit the surface and reflected towards a new location. It therefore bounced off.
