Answer:
The initial velocity of the ball is <u>39.2 m/s in the upward direction.</u>
Explanation:
Given:
Upward direction is positive. So, downward direction is negative.
Tota time the ball remains in air (t) = 8.0 s
Net displacement of the ball (S) = Final position - Initial position = 0 m
Acceleration of the ball is due to gravity. So, 
(Acting down)
Now, let the initial velocity be 'u' m/s.
From Newton's equation of motion, we have:
Plug in the given values and solve for 'u'. This gives,
Therefore, the initial velocity of the ball is 39.2 m/s in the upward direction.
Answer:
5 × 10¹⁰ or 5 billion times louder is the intensity of sound at a rock concert in comparison with that of a whisper
Explanation:
Given that at a rock concert;
the intensity of sound is 110 dB compared to a whisper of 3 dB
Now; how many times louder will that of the whisper be compared to the sound of the rock concert
Using the formula for calculating decibels (dB);
For 110 dB
dB = 10log₁₀(W)
110 dB = 
110 dB = 10¹¹
For 3dB
dB = 10log₁₀(W)
3 dB = 
3 dB = 2
Now:
(110/3)dB = 10¹¹/2
(110/3)dB = 5 × 10¹⁰ or 5 billion times louder is the intensity of sound at a rock concert in comparison with that of a whisper
The gravitational force of attraction between two objects would be increased by "decreasing the distance between two objects"
Hope this helps!
