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murzikaleks [220]
3 years ago
11

A person driving her car at 48 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). Should she try to stop, or should she make a run for it? The intersection is 15 m wide. Her car's maximum deceleration is -7.0 m/s2, whereas it can accelerate from 48 km/h to 70 km/h in 6.6 s. Ignore the length of her car and her reaction time. If she hits the brakes, how far will she travel before stopping?
Physics
1 answer:
trasher [3.6K]3 years ago
4 0

Answer:

She must stop the car  before interception, distance traveled 12.66 m

Explanation:

We will take all units to the SI system

Vo = 48Km / h (1000m / 1Km) (1h / 3600s) = 13.33 m / s

V2 = 70 Km / h = 19.44 m / s

We calculate the distance traveled before stopping

X = Vo t + ½ to t²

Time is what it takes traffic light to turn red  is t = 2.0 s

X = 13.33 2 + 1.2 (-7) 2²

X = 12.66 m

It stops car before reaching the traffic light turning to red

Let's analyze what happens if you accelerate, let's calculate the acceleration of the vehicle

     V2 = Vo + a t2

      a = (V2-Vo) / t2

      a = (19.44-13.33) /6.6

      a = 0.926 m / s2

This is the acceleration to try to pass the interception, now let's calculate the distance it travels in the time the traffic light changes from yellow to red (t = 2.0 s)

X = Vo t + ½ to t²

X = 13.33 2 + ½ 0.926 2²

X = 28.58 m

Since the vehicle was 30 m away, the interception does not happen

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Shkiper50 [21]

The force required to extend a rod increases as the cross sectional area

increases.

The rod that experiences the largest force is <u>rod B</u>

Reason:

The elongation of a rod by the application of a force is given by the

following formula;

\Delta L = \dfrac{F \cdot L}{A \cdot E}

From the above equation, we have that the elongation is inversely

proportional to the cross sectional area, such that the extension of a rod by

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Therefore, the force required to extend the length of a rod by a specific

amount increases as the cross sectional area of the rod increases,

indicating that the rod with the largest cross sectional area require the

most force and therefore, experiences the largest force.

The rod that experiences the largest force is the rod with the largest cross

sectional area, which is <u>rod B</u>

Learn more here:

brainly.com/question/12937199

4 0
2 years ago
what is the initial velocity of a go-kart traveling at a uniform acceleration of 0.5 m/s^2 for 5s as it slows down to a stop?​
timurjin [86]

The initial velocity of go-kart is 2.5 m/s.

<u>Explanation:</u>

Here, the uniform acceleration of go-kart is given as 0.5 m/s². Also the time required by it to stop is also given as 5 s. As acceleration is the measure of change in velocity per unit time.

In this case, the velocity should be changed from a value to zero to come to rest. So the initial velocity will be positive value and final velocity is zero.

As we know the values of acceleration, final velocity and time, the initial velocity can be easily determined as follows.

Acceleration = \frac{Final velocity -Initial velocity}{Time}

Since, final velocity is zero, acceleration is 0.5 m/s² and time is 5 s, then,

        -0.5=\frac{-\text {Initial velocity}}{5}

        Initial velocity = 0.5 × 5 = 2.5 m/s.

So the initial velocity of go-kart is 2.5 m/s.

8 0
3 years ago
2<br><br> How does Descartes' "quality of motion" differ from the modern<br><br> momentum?
Rzqust [24]

Answer: Descartes was more of speed which defers from modern day velocity.

Explanation:

Descartes law if conservation referred or defined “motion” rather than “momentum” as what is obtainable in today's world as ”speed” the rate at which something moves rather than “velocity” which is a product of speed and direction. So in conclusion Descartes was more of speed which defers from modern day velocity.

6 0
3 years ago
The density of gold is 19.3 g cm³. What is the mass of a bar of gold in Kg that measures 6 cm x 4 cmx to 2 cm ?
klemol [59]

Answer: 0.9264 kg

Explanation: [I'll use "cc" for cubic centimeter, instead of cm^3.

The volume is 6cm*4cm*2cm = 48 cm^3 (cc).

Density of Au is 19.3 g/cc

Mass of gold = (48 cc)*(9.3 g/cc) = 926.4 grams Au

1 kg = 1,000 g

(926.4 grams Au)*(1 kg/1,000 g) = 0.9264 kg, 0.93 kg to 2 sig figs

At gold's current price of $57,500/kg, this bar is worth $53,268. Keep it hidden from your lab partner (and instructor).

3 0
3 years ago
If we drop different weights from same height which will fall first to ground? Both of them hit the ground at the same time righ
crimeas [40]
Yes tthey would both hit the ground
5 0
3 years ago
Read 2 more answers
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