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denis-greek [22]
3 years ago
9

A car travels 100 m while decelerating to 8 m/s in 5 s. a) What was its initial speed?

Physics
1 answer:
viktelen [127]3 years ago
6 0

Answer:

Vi = 32 [m/s]

Explanation:

In order to solve this problem we must use the following the two following kinematics equations.

v_{f} =v_{i} - (a*t)\\

The negative sign of the second term of the equation means that the velocity decreases, as indicated in the problem.

where:

Vf = final velocity = 8[m/s]

Vi = initial velocity [m/s]

a = acceleration = [m/s^2]

t = time = 5 [s]

Now replacing:

8 = Vi - 5*a

Vi = (8 + 5*a)

As we can see we have two unknowns the initial velocity and the acceleration, so we must use a second kinematics equation.

v_{f}^{2} = v_{i}^{2} - (2*a*d)

where:

d = distance = 100[m]

(8^2) = (8 + 5*a)^2 - (2*a*100)

64 = (64 + 80*a + 25*a^2) - 200*a

0 = 80*a - 200*a + 25*a^2

0 = - 120*a + 25*a^2

0 = 25*a(a - 4.8)

therefore:

a = 0 or a = 4.8 [m/s^2]

We choose the value of 4.8 as the acceleration value, since the zero value would not apply.

Returning to the first equation:

8 = Vi - (4.8*5)

Vi = 32 [m/s]

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Answer:

Check the explanation

Explanation:

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b) f = n v / 4 L

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f = 7 x 350 / 4 x 0.41 = 1493.9 Hz

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Using, f = n v / 4 Leff

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What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased?
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Answer:

The pressure will be transmitted equally to all other parts of the confined fluid causing a general increase in pressure throughout the container.

Explanation:

This is in line with pascal's law of pressure which states that the pressure exerted on a given mass of fluid is transmitted undiminished to other parts of the fluid.

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220V is applied to two different conductors made of the same material. One conductor is twice as long and twice as thick as the
ollegr [7]

Answer:

Explanation:

For calculating resistance of a conductor , the formula is

R = ρ l / A , ρ is specific resistance , l is length and A is cross sectional area of wire.

For first wire length is l₁ , area is A₁ resistance is R₁, for second resistance is R₂ , length is l₂ and area is A₂

Given , l₁ = 2l₂ , A₁ = 4A₂ , area is proportional to square of thickness.

R₁ / R₂ = I₁A₂ / I₂A₁

= 2l₂ x A₁ / 4 I₂A₁

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Ratio of power = (V² / R₁) x (R₂ / V²)

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Naily [24]

Answer:

The value of the centripetal forces are same.

Explanation:

Given:

The masses of the cars are same. The radii of the banked paths are same. The weight of an object on the moon is about one sixth of its weight on earth.

The expression for centripetal force is given by,

F_{c} = \dfrac{mv^{2}}{r}

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The value of the centripetal force depends on the mass of the object, not on its weight.

As both on moon and earth the velocity of the cars and the radii of the paths are same, so the centripetal forces are the same.

3 0
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