Answer:
it is very hard question for me sorry i cant solve it
Answer:Reducing mass i.e. water
Explanation:
Frequency For given mass in glass is given by

where k =stiffness of the glass
m=mass of water in glass
from the above expression we can see that if mass is inversely Proportional to frequency
thus reducing mass we can increase frequency
Gravity
The moon doesn't smash into the earth because the gravity from the earth keeps the moon in orbit around it.
Answer:
Explanation:
If a perfect vacuum existed in any volume, then no sound would be able to propagate through it, because a sound wave is a pressure wave, and there would be identically zero pressure. Of course, we could get into speculations about “dark energy” or “vacuum energy” supporting pressure waves, but let’s not go there.
Answer:
20 N
Explanation:
By Newton's 2nd law,
The rate of change of momentum is directly proportional to the unbalance force applied on the object,
By that you can get the equation,
F = ma
= 5 × 4 = 20 N