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Answer:
The sound intensity of train is 1000 times greater than that of the library.
Explanation:
We have expression for sound intensity level,

A train whistle has a sound intensity level of 70 dB
We have

A library has a sound intensity level of about 40 dB
We also have

Dividing both equations

The sound intensity of train is 1000 times greater than that of the library.
Answer:
The maximum height the pebble reaches is approximately;
A. 6.4 m
Explanation:
The question is with regards to projectile motion of an object
The given parameters are;
The initial velocity of the pebble, u = 19 m/s
The angle the projectile path of the pebble makes with the horizontal, θ = 36°
The maximum height of a projectile,
, is given by the following equation;

Therefore, substituting the known values for the pebble, we have;

Therefore, the maximum height of the pebble projectile,
≈ 6.4 m.
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Answer:
<h2>9.3kN</h2>
Explanation:
Step one:
given data
mass of bullet= 0.02kg
speed v=700m/s
time taken =1.5ms= 0.0015 seconds
Step two:
we know that from the first law
F=ma-----1 first law of motion
also, we know that
a=v/t----2
put a=v/t in equation 1 we have
F=mv/t
Step three:
substitute our given data to find force
F=0.02*700/0.0015
F=14/0.0015
F=9333.33N
F=9.3kN
<u>The average force exerted is 9.3kN</u>