<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>
We know, Period = 1/frequency = 1/20 sec.
So, your final answer is 0.05 sec
Hope this helps!
Answer:
40 Hz
Explanation:
f = 1/T = 1 / 0.025 = 40 Hz
Answer:
just before landing the ground
Explanation:
Let the velocity of projection is u and the angle of projection is 30°.
Let T is the time of flight and R is the horizontal distance traveled. As there is no force acting in horizontal direction, so the horizontal velocity remains constant. Let the particle hits the ground with velocity v.
initial horizontal component of velocity, ux = u Cos 30
initial vertical component of velocity, uy = u Sin 30
Time of flight is given by

Final horizontal component of velocity, vx = ux = u Cos 30
Let vy is teh final vertical component of velocity.
Use first equation of motion
vy = uy - gT


vy = - u Sin 30
The magnitude of final velocity is given by


v = u
Thus, the velocity is same as it just reaches the ground.