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Xelga [282]
3 years ago
13

A traffic accident detective measures the skid marks left by a car, 825kg. He determines that the distance between the point tha

t the driver slammed on the brakes and the point where the car came to a stop was 34.0 m. From a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. How fast was the car going when the driver applied the brakes? (This car was not equipped with anti-lock brakes.
Physics
1 answer:
deff fn [24]3 years ago
7 0
Doing a force balance on the car:
ma = Fr
ma = μmg
a = μg
a = 0.3(9.81)
a = 29.43 m/s2

Using the formula:
2ax = v2
2(29.43)(34) = v2
v = 44.74 m/s = 161.05 km/h

The car was going 44.74 m/s or 161.05 kph when the brakes were applied.
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C - Branden believes that he is not okay unless he is perfect.

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2 years ago
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Can you think of a scenario when the kinetic and gravitational potential energy could both be zero ? Describe or draw how this c
Inga [223]

Both kinetic and gravitational potential energy can become zero at infinite distance from the Earth.

Consider an object  of mass <em>m </em>projected from the surface of the Earth with a velocity <em>v. </em>

The total energy of the body on the surface of the Earth is the sum of its kinetic energy \frac{1}{2} mv^2and gravitational potential energy -\frac{GMm}{R^2}.

here, <em>M</em> is the mass of the Earth, <em>R</em> is the radius of Earth and <em>G</em> is the universal gravitational constant.

The gravitational potential energy of the object is negative since it is in an attractive field, which is the gravitational field of the Earth.

The energy of the object on the surface of the earth is given by,

E_i=\frac{1}{2} mv^2-\frac{GMm}{R^2}

As the object rises upwards, it experiences deceleration due to the gravitational force of the Earth. Its velocity decreases and hence its kinetic energy decreases.

The decrease in kinetic energy is manifested as  an equal increase in potential energy. The potential energy becomes less and less negative as more and more kinetic energy is converted into potential energy.

At a height <em>h</em> from the surface of the Earth, the energy of the object is given by,

E_h=\frac{1}{2} mv_h^2-\frac{GMm}{(R+h)^2}

The velocity v_h is less than <em>v</em>.

When h =∞, the gravitational potential energy increases from a negative value to zero.

If the velocity of projection is adjusted in such a manner that the velocity decreases to zero at infinite distance from the earth, the object's kinetic energy also becomes equal to zero.

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7 0
3 years ago
The law of conservation of matter states that matter can be neither created nor destroyed. Your friend shows you the following c
MrRa [10]

Yes, our friend is right, because there is no contradiction to the law of conservation of mass in the above equation. It just the mass of the product is equal to the mass of reactants.. and that is shown in the equation you have presented earlier

7 0
3 years ago
Question 2 of 10
Arlecino [84]

Answer:

B: Energy that is transformed is neither created or destroyed

Explanation:

4 0
2 years ago
If an oscillating mass has a frequency of 1.25 Hz, it makes 100 oscillations in
KatRina [158]

Answer:

Time, t = 80 seconds

Explanation:

Given that,

The frequency of the oscillating mass, f = 1.25 Hz

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We need to find the time in which it makes 100 oscillations. We know that the frequency of an object is number of oscillations per unit time. It is given by :

f=\dfrac{n}{t}

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t=\dfrac{100}{1.25\ Hz}

t = 80 seconds

So, it will make 100 oscillations in 80 seconds. Hence, this is the required solution.

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3 years ago
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