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elena-14-01-66 [18.8K]
3 years ago
8

The driver of a car going 86.0 km/h suddenly sees the lights of a barrier 44.0 m ahead. It takes the driver 0.75 s to apply the

brakes, and the average acceleration during braking is -10.0 m/s2.
(a) Determine whether the car hits the barrier.

(b) What is the maximum speed at which the car could be moving and not hit the barrier 44.0 m ahead? Assume that the acceleration doesn't change.
Physics
1 answer:
Lynna [10]3 years ago
7 0

Part a

Answer: NO

We need to calculate the distance traveled once the brakes are applied. Then we would compare the distance traveled and distance of the barrier.

Using the second equation of motion:

s=ut+0.5at^2

where s is the distance traveled, u is the initial velocity, t is the time taken and a is the acceleration.

It is given that, u=86.0 km/h=23.9 m/s, t=0.75 s, a=-10.0 m/s^2

\Rightarrow s=23.9 m/s \times 0.75s+0.5\times (-10.0 m/s^2)\times (0.75 s)^2=15.11 m

Since there is sufficient distance between position where car would stop and the barrier, the car would not hit it.

Part b

Answer: 29.6 m/s

The maximum distance that car can travel is s=44.0 m

The acceleration is same, a=-10.0 m/s^2

The final velocity, v=0

Using the third equation of motion, we can find the maximum initial velocity for car to not hit the barrier:

v^2-u^2=2as

0-u^2=-2 \time 10.0m/s^2 \times 44.0 m\Rightarrow u=\sqrt{880 m^2/s^2}=29.6 m/s

Hence, the maximum speed at which car can travel and not hit the barrier is 29.6 m/s.





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Zielflug [23.3K]

Incomplete question.The complete question is attached below as screenshot along with figure

Answer:

F=6.00*10^{-6}N

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Explanation:

Given data

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From repulsive force we know that:

F=\frac{u_{o}I_{1}I_{2}L}{2\pi r}

Substitute the given values

F=\frac{u_{o}(5.00A)(2.00A)(1.20m)}{2\pi (0.400m)}\\ F=6.00*10^{-6}N

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A block of ice at 0 degrees C, whose mass is initially 62 kg, slides along a horizontal surface, starting at a speed of 5.48 m/s
Kryger [21]

The mass of ice melted as a result of friction between the ice and the horizontal surface is 2.78g

<u>Explanation:</u>

Given,

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Distance, x = 26.8m

Friction is present.

Mass of ice melted = ?

We know,

The amount of energy required for the melting of ice is exactly equal to the initial kinetic energy of the block of ice

and

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Therefore,    KE = \frac{62 X  5.48 X 5.48}{2}

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Therefore, the melted mass of the ice = 930.94 / 334000 = 0.00278 kg = 2.78 g.

Thus, The mass of ice melted as a result of friction between the ice and the horizontal surface is 2.78g

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3 years ago
A plane has a takeoff speed of 88.3 m/s and can accelerate at a rate of 3m/s to reach that speed. How long does the plane take t
Mrrafil [7]

v = \frac{d}{t}

and

a = \frac{v}{t}

We have acceleration and velocity so:

3 = \frac{v}{t}

88.3 = \frac{d}{t}

In the acceleration equation we can isolate for v and then plug it back into the other equation to solve...

So...

3t = v

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Which of newton's three laws is the hardest to describe or explain when viewing common occurrences?
choli [55]

Newton's second law is the hardest to describe as it is about momentum  (F = ma), and a lot of people don't know the concept of momentum.

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Newton's 3rd law of motion:- For every action, there's an equal and opposite reaction.

learn more about Newton's first law of motion here brainly.com/question/10454047

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