Answer:
Explanation:
velocity of sound in air at 20⁰C is 343 m /s
velocity of sound in water at 20⁰C is 1481 m /s
The wavelength of the sound is 2.86 m in the air so its frequency
= 343 / 2.86 = 119.93 .
This frequency of 119.93 will remain unchanged in water .
wavelength in water = velocity in water / frequency
= 1481 / 119.93
= 12. 35 m .
Answer:
3. Work
Explanation:
Number 1 isn't correct because you are not using efficiency to hold books and walk across the room.
Number 2 could be correct but isn't in this situation because you use power only to hold the books but not to walk across the room.
Number 4 is not correct because you need to do work to do something.
The role of friction is of great importance when creating safety ramps and escalators because with the help of friction things move.
<h3>Why is it important to move objects slowly on ramps and escalator?</h3>
It is important to move objects slowly on ramps and escalator because the ramps and escalator moves object in the opposite direction of gravity. If we did not move objects slowly, then the objects or a person get damaged.
So we can conclude that the role of friction is of great importance when creating safety ramps and escalators because with the help of friction things move.
Learn more about friction here: brainly.com/question/24338873#SPJ1
I’m pretty sure that it’s D