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iVinArrow [24]
2 years ago
6

The driver of a 810.0 kg car decides to double the speed from 23.6 m/s to 47.2 m/s. What effect would this have on the amount of

work required to stop the car, that is, on the kinetic energy of the car? KEi= × 105 J KEf= × 105 J times as much work must be done to stop the car.
Mathematics
1 answer:
Setler [38]2 years ago
8 0

Answer:

  • KEi = 2.256×10^5 J
  • KEf = 9.023×10^5 J
  • 4 times as much work

Step-by-step explanation:

The kinetic energy for a given mass and velocity is ...

  KE = (1/2)mv^2 . . . . . m is mass

At its initial speed, the kinetic energy of the car is ...

  KEi = (1/2)(810 kg)(23.6 m/s)^2 ≈ 2.256×10^5 J . . . . . m is meters

At its final speed, the kinetic energy of the car is ...

  KEf = (1/2)(810 kg)(47.2 m/s)^2 ≈ 9.023×10^5 J

The ratio of final to initial kinetic energy is ...

  (9.023×10^5)/(2.256×10^5) = 4

4 times as much work must be done to stop the car.

_____

You know this without computing the kinetic energy. KE is proportional to the square of speed, so when the speed doubles, the KE is multiplied by 2^2 = 4.

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Adam dropped a rubber ball from a window 40 ft above the sidewalk the ball always bounces half of the height that it drops how f
sergij07 [2.7K]

Answer:

The ball will reach a height of 5 ft by the 4th time.

Step-by-step explanation:

The initial height of the ball is 40 ft, when it bounces from the floor once the height will be 20 ft, the second time it'll be 10 ft, and so on. The sequence that can represent the maximum height of the ball after each bounce is:

{40, 20, 10,...}

This kind of sequence is called a geometric progression, in this kind of progression the next number is related to the one before it by the product of a constant called ratio, in this case 1/2. To calculate a specific position in this sequence we only need the ratio and the first number, using the formula below:

a_n = a*r^(n-1)

Where n is the position we want to know, a is the first number and r is the ratio. In this case we have:

a_4 = 40*(1/2)^(4-1) = 40*(1/2)^3 = 40/8 = 5

The ball will reach a height of 5 ft by the 4th time.

6 0
3 years ago
A 4-bedroom, 4-bath 4,875 square feet house was listed at $445,000. Andreas, the seller, accepted an offer that was 95% of the l
klasskru [66]

Answer: He gets $86.71 per square foot

Step-by-step explanation:

Hi, to answer this question we have to analyze the information given:

<em>Area = 4,875 square feet </em>

<em>Price = $445,000 </em>

First, we have to divide the price of the house by the area, to obtain the price per square foot:

Mathematically speaking:

$445,000 / 4,875 square feet = $91.2 per square foot (original price)

Now we have to multiply it by the offer in decimal form (95/100 =0.95)

$91.2 x 0.95 = 86.71 per square foot

He gets $86.71 per square foot.

Feel free to ask for more if needed or if you did not understand something.

8 0
3 years ago
Mike wants to find the confidence interval for a set of data. He knows the sample size and the sample proportion. Which other pi
ASHA 777 [7]

Answer:

A

Step-by-step explanation:

6 0
2 years ago
I WILL GIVE BRAINLIEST TO WHOEVER IS CORRECT
irinina [24]

the third choice is correct


6 0
2 years ago
The​ x-value(s) for which ​f(x)​g(x) ​is/are ___
Maslowich

9514 1404 393

Answer:

  x = -1, 1, 9

Step-by-step explanation:

You want x such that f(x) = g(x). Subtracting g(x) from both sides of this equation lets us rewrite it as ...

  f(x) -g(x) = 0

  x³ -9x² -(x -9) = 0

  x²(x -9) -1(x -9) = 0 . . . factor the first pair of terms

  (x² -1)(x -9) = 0 . . . . . . use the distributive property

  (x -1)(x +1)(x -9) = 0 . . . . factor the difference of squares

Values of x that make these factors zero will make f(x) = g(x):

  x = -1, 1, 9 for f(x) = g(x)

7 0
3 years ago
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