Willie Swift drives a hockey puck into the goal at a speed of 34.8 m/s. From a distance of 60.0 m, how long will it take to reac
1 answer:
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Given data:
* The mass of the book is 2 kg.
* The initial height of the book is 0.78 m.
* The final height of the book is 2.1 m.
Solution:
(A). The work done by the gravity on the book is,
where m is the mass, g is the acceleration due to gravity, h_i is the initial height and h_f is the final height,
The work is done in moving the object in upward direction where as the gravitational force is acting in the down ward direction. Thus, the value g (acceleration due to gravity) is taken as negative in this case.
Substituting the known values,
Thus, the work done by the gravitational force is -25.9 J.
(B). The work done by the hand on the moving the book is,
Thus, the work done by the hand on the book is 25.9 J.
Answer:
required distance is 233.35 m
Explanation:
Given the data in the question;
Sound intensity = 1.62 × 10⁻⁶ W/m²
distance r = 165 m
at what distance from the explosion is the sound intensity half this value?
we know that;
Sound intensity is proportional to 1/(distance)²
i.e
∝ 1/r²
Now, let r² be the distance where sound intensity is half, i.e ₂ =
₁/2
Hence,
₂/
₁ = r₁²/r₂²
1/2 = (165)²/ r₂²
r₂² = 2 × (165)²
r₂² = 2 × 27225
r₂² = 54450
r₂ = √54450
r₂ = 233.35 m
Therefore, required distance is 233.35 m