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DanielleElmas [232]

3 years ago

15

if a bullet fired beneath the water, straight up, breaks through the surface at a speed of 25m/s, how high will the bullet be af

ter 2.8 seconds? what is the bullet's velocity at this time? (accelaration of 9.8m/s)

1 answer:

Doss [256]3 years ago

8 0

Answer:

32 m and -2.4 m/s

Explanation:

Given:

v₀ = 25 m/s

t = 2.8 s

a = -9.8 m/s²

Find: Δy, v

Δy = v₀ t + ½ at²

Δy = (25 m/s) (2.8 s) + ½ (-9.8 m/s²) (2.8 s)²

Δy = 31.6 m

v = at + v₀

v = (-9.8 m/s²) (2.8 s) + 25 m/s

v = -2.44 m/s

Rounded to two significant figures, the bullet reaches a height of 32 m and a velocity of -2.4 m/s.

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Answer:

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Part(b): the radius of the inner sphere is 3.1 cm.

Part(c): the electric field just outside the surface of inner sphere is $\bf{2.81 \times 10^{4}~n~C^{-1}}$ .

Explanation:

We know that if 'a' and 'b' are the inner and outer radii of the shell respectively, 'Q' is the total charge contains by the capacitor subjected to a potential difference of 'V' and ' $\epsilon_{0}$ ' be the permittivity of free space, then the capacitance (C) of the spherical shell can be written as

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$C &=& \dfrac{Q}{V} = \dfrac{3 \times 10^{-90}~C}{230~V} = 1.3 \times 10^{-11}~F = 0.013~nF$

Part(b):

Given the inner radius of the outer shell b = 4.3 cm = 0.043 m. Therefore, from equation (1), rearranging the terms,

$&& \dfrac{1}{a} = \dfrac{1}{b} + \dfrac{1}{C/4 \pi \epsilon_{0}} = \dfrac{1}{0.043} + \dfrac{1}{1.3 \times 10^{-11} \times 9 \times 10^{9}} = 31.79\\&or,& a = \dfrac{1}{31.79}~m = 0.031~m = 3.1~cm$

Part(c):

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Answer:

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We know that

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