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viva [34]
3 years ago
13

A person driving her car at 43 km/h approaches an intersection just as the traffic light turns yellow. She knows that the yellow

light lasts only 2.0 s before turning to red, and she is 30 m away from the near side of the intersection (Fig. 2-29). The intersection is 15 m wide. Her car's maximum deceleration is -5.4 m/s2, whereas it can accelerate from 43 km/h to 70 km/h in 8.1 s. Ignore the length of her car and her reaction time.Figure 2-29If she hits the brakes, how far will she travel before stopping?
If she hits the gas instead, how far will she travel before the light turns red?m Should she try to stop, or should she speed up to cross the intersection before the light turns red?
Physics
1 answer:
siniylev [52]3 years ago
5 0

Answer:

If she hits the brakes, she will travel 13m before stopping. If she hits the gas, she will travel 28 before the light turns red. She should try to stop

Explanation:

To know how far she will travel before stopping, we need to use a kinematic formula which initial final velocity (Vf), initial velocity (V0), acceleration (a) and distance traveled(x):

V_{f}^{2}=V_{0} ^{2} +2ax

The moment in which she stops is when the final velocity equals zero. In this case, initial velocity is 43km/h=12m/s, and its maximum deceleration is -5.4m/s^2. Plugging in these values and solving for x:

0^2=(12m/s)^2+2(-5.4m/s)x\\x=13m

She will travel 13m before stopping

If she hits the gas, we need another kinematic formula, which relates distance traveled, initial speed, time (t) and acceleration.

x=v_{0}t+0.5a*t^2

If we know her car can accelerate from 43km/h=12m/s to 70km/h=19m/s in 8.1 s, we can know its acceleration:

a=\frac{19m/s-12m/s}{8.1s}=0.86m/s^2

In this case, the time before the light turns red is 2.0s. Plugging in all those values:

x=12m/s*2s+0.5*0.86m/s^2*(2s)^2=28m

If she hits the gas, she will travel 28m before the light turns red. She won't even reach the intersection, so she would try to stop.

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What explains the information needed to calculate speed and velocity?
Ede4ka [16]
To calculate speed, you need to know the total distance covered
and the time it took to cover the distance.

To calculate velocity, you need the starting location, the ending location,
and the time it took to go from start to finish.

3 0
3 years ago
A man is using a fishing rod to catch fish in figure 1.
ryzh [129]

Answer:

Explanation:

Remark

In general, these 3rd class levers are very inefficient. Because the force distance is smaller than the load distance, you need to pull upward with more force that the weight of the load. So whatever the load is, the force is going to be much greater.

The distances are always measured to the pivot unless you are asked something specific otherwise.

Givens

F = ?

weight = 6N

Force Distance = F*d = 0.5 m

Weight Distance =W*d1 = 2 m

Formula

F*Fd = W*Wd

Solution

F*0.5 = 6 * 2            Divide by 0.5

F = 12/0.5

F = 24 N upwards

5 0
2 years ago
Minority group
Margarita [4]

Answer:

Minority group - People who are singled  out for unequal treatment  and who regard  themselves as objects of  collective discrimination.

Ethnicity - A shared identity based on  cultural elements such as  heritage, language, and  religion.

Majority group - A group's subset that  consists of more than half  of the entire group's  members.

Race - A socially constructed  group of people who share  physical characteristics  that are considered  significant by a society  and that are used to  distinguish them from  other groups.

Explanation:

To better understand the above-mentioned definitions we would use some examples:

Elder people can be considered as a minority group in the United States because of their reduced status as a consequence of popular discrimination and prejudice against them. In contrast to them, young men consisting of more than half the population in the age category is an example of the majority group.

Groups of people like Hispanic Americans, Jews, Italian America, Irish are some examples of people belonging to different ethnic backgrounds residing in the U.S.

African Americans who are distinguished based on their skin color is an example of race.

6 0
3 years ago
A pair of slits separated by 1 mm, are illuminated with monochromatic light of wavelength 411 nm. The light falls on a screen 1.
Ilya [14]

Answer:

t = 0.192 \mu m

Explanation:

Path difference due to a transparent slab is given as

\Delta x = (\mu - 1) t

here we know that

\mu = 1.79

now total shift in the bright fringe is given as

Shift = \frac{D(\mu - 1)t}{d}

Also we know that the fringe width of maximum intensity is given as

\delta x = \frac{\lambda D}{d}

now we have

\frac{D}{d} = \frac{\delta x}{\lambda}

now the shift is given as

Shift = \frac{(\mu - 1) t \delta x}{\lambda}

given that the shift is

Shift = 0.37 \delta x

here we have

0.37 \delta x = \frac{(\mu - 1) t \delta x}{\lambda}

now plug in all values in it

0.37 = \frac{(1.79 - 1) t}{411 \times 10^{-9}}

t = 0.192 \times 10^{-6} m

t = 0.192 \mu m

3 0
3 years ago
The pressure inside a blimp is 506 Pa, if the area is 3,000cm2 then what is the force? ​
Zarrin [17]

Answer:

<h2>151.8 N</h2>

Explanation:

The force acting on the blimp can be found by using the formula

<h3>f = p × a</h3>

p is the pressure

a is the area

3000 cm² = 0.3 m²

From the question we have

f = 506 × 0.3

We have the final answer as

<h3>151.8 N</h3>

Hope this helps you

6 0
3 years ago
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