Answer:
The height of the cliff is, h = 78.4 m
Explanation:
Given,
The horizontal velocity of the projectile, Vx = 20 m/s
The range of the projectile, s = 80 m
The projectile projected from a height is given by the formula
<em> S = Vx [Vy + √(Vy² + 2gh)] / g
</em>
Therefore,
h = S²g/2Vx²
Substituting the values
h = 80² x 9.8/ (2 x 20²)
= 78.4 m
Hence, the height of the cliff is, h = 78.4 m
Answer:
The new intensity decreases by a factor of 16.
Explanation:
The intensity of sound wave is given by :

P is power
A is area

or
, r is distance from the source
If the distance from the source is increased by a factor of 4, r' = 4r
So,

So, the new intensity decreases by a factor of 16.
Answer is: <span>1/4 its old kinetic energy .
</span>V₁ = 10 m/s.
V₂ = 5 m/s.
m₁ = m₂ = m.
E₁ = 1/2 · m₁ · V₁², E₁ = 1/2 · m · (10 m/s)² = 50 · m.
E₂ = 1/2 · m₂ · V₂², E₂ = 1/2 · m · (5 m/s)² = 12,5 · m.
E₂/E₁ = 12,5m / 50m = 0,25.
V - speed of semi-truck.
m - mass of semi-truck.
E - kinetic energy of semi-truck.
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