Ask question

Ask question

All categories

3 years ago

8

Being 10 miles apart, two cars started moving towards each other. After one hour they met, and during that time the first car co

vered 2 miles more than the second car. What was the speed of the first car?

2 answers:

Vladimir [108]3 years ago

7 0

The speed of the first car was 6 miles/hour

<h3>Further explanation</h3>

Acceleration is rate of change of velocity.

$\large {\boxed {a = \frac{v - u}{t} } }$

$\large {\boxed {d = \frac{v + u}{2}~t } }$

<em>a = acceleration ( m/s² )</em>

<em>v = final velocity ( m/s )</em>

<em>u = initial velocity ( m/s )</em>

<em>t = time taken ( s )</em>

<em>d = distance ( m )</em>

Let us now tackle the problem!

<u>Given:</u>

Distance between two cars = d = 10 miles

Time Taken = t = 1 hour

Distance covered by the first car = d₁ = 2 + d₂

<u>Unknown:</u>

Speed of the first car = v₁ = ?

<u>Solution:</u>

$d = d_1 + d_2$

$10 = ( 2 + d_2 ) + d_2$

$10 = 2 + 2d_2$

$10 - 2 = 2 d_2$

$8 = 2 d_2$

$d_2 = 8 \div 2$

$d_2 = 4 \texttt{ miles}$

$\texttt{ }$

$d_1 = 2 + d_2 = 2 + 4 = 6 \texttt{ miles}$

$v_1 = d_1 \div t = 6 \div 1 = 6 \texttt{ miles/hour}$

<h3>Learn more</h3>

Velocity of Runner : brainly.com/question/3813437
Kinetic Energy : brainly.com/question/692781
Acceleration : brainly.com/question/2283922
The Speed of Car : brainly.com/question/568302

<h3>Answer details</h3>

Grade: High School

Subject: Physics

Chapter: Kinematics

Keywords: Velocity , Driver , Car , Deceleration , Acceleration , Obstacle

guapka [62]3 years ago

7 0

The speed of the first car is $\boxed{6{\text{ mph}}}$ and the speed of the second car is $\boxed{4{\text{ mph}}}.$

Further explanation:

The formula of the speed can be expressed as follows,

$\boxed{{\text{Speed}} = \frac{{{\text{Distance}}}}{{{\text{Time}}}}}$

The formula of the time can be expressed as follows,

$\boxed{{\text{Time}} = \frac{{{\text{Distance}}}}{{{\text{Speed}}}}}$

Given:

The distance between the two cars is $10{\text{ miles}}.$

The first car covered 2 miles more than the second car.

Explanation:

Consider the speed of the second car be “ $x$ ”.

Consider the speed of the first car be “ $x+2$ ”.

The distance covered by the first car in one hour is $x + 2{\text{ miles}}.$

The distance covered by the second car in one hour is $x{\text{ miles}}.$

The total distance covered by two cars is $10{\text{ miles}}.$

$\begin{aligned}x + 2 + x &= 10\\2x + 2 &= 10\\2x &= 10 - 2\\2x &= 8\\x&= 4\\\end{aligned}$

The speed of the second car is $4{\text{ miles/h}}.$

The speed of the first car can be obtained as follows,

$\begin{aligned}{\text{Speed}} &= x + 2\\&= 4 + 2\\&= 6{\text{ miles/h}}\\\end{aligned}$

The speed of the first car is $\boxed{6{\text{ mph}}}$ and the speed of the second car is $\boxed{4{\text{ mph}}}.$

Learn more:

1. Learn more about inverse of the functionhttps://brainly.com/question/1632445.

2. Learn more about equation of circle brainly.com/question/1506955.

3. Learn more about range and domain of the function brainly.com/question/3412497

Answer details:

Grade: High School

Subject: Mathematics

Chapter: Speed and Distance

Keywords: 10 miles, speed of first car, speed of the second car, after one hour, moving toward, each other, 2 miles per hour, one hour.

You might be interested in

Clare has 5 yards of ribbon. It takes 1/2 yard to make a bow. How many bows can Clare make with the ribbon? Write a multiplicati

KonstantinChe [14]

Answer:

10 yards (Add label!!)

Step-by-step explanation:

5x1/2=10

8 0

2 years ago

Which shows the expression below simplified? 0.00048 - (3.4 × 10-5) A. 4.46 × 10-4 B. 3.39952 × 10-5 C. 4.46 × 10-5 D. 1.4 × 10-

MakcuM [25]

Option C

The simplified form of given expression is $4.46 \times 10^{-4}$

<em><u>Solution:</u></em>

Given that we have to simplify the expression shown below

$0.00048 - (3.4 \times 10^{-5})$

Let us first convert 0.00048 to scientific notation

<em><u>Steps to follow:</u></em>

Move the decimal point in your number until there is only one non-zero digit to the left of the decimal point. The resulting decimal number is a.

Count how many places you moved the decimal point. This number is b.

If you moved the decimal to the left b is positive.

If you moved the decimal to the right b is negative.

If you did not need to move the decimal b = 0.

Write your scientific notation number as a x 10^b and read it as "a times 10 to the power of b."

Remove trailing 0's only if they were originally to the left of the decimal point.

$0.00048 = 4.8 \times 10^{-4}$

So the given expression becomes,

$\rightarrow 4.8 \times 10^{-4} - 3.4 \times 10^{-5}$

Let us make the exponent of second term as -4

$\rightarrow 4.8 \times 10^{-4} - 0.34 \times 10^{-4}$

Take $10^{-4}$ as common term,

$\rightarrow 10^{-4} (4.8 - 0.34)$

$\rightarrow 4.46 \times 10^{-4}$

Thus option C is correct

7 0

3 years ago

Simplify the following expression by combining like terms. Select the most simplified expression

Jet001 [13]

Answer:

It is D

Step-by-step explanation:

Distribute:

=(4)(5m)+(4)(3)+2m

=20m+12+2m

Combine Like Terms:

=20m+12+2m

=(20m+2m)+(12)

=22m+12

8 0

3 years ago

Consider the equation below. (If an answer does not exist, enter DNE.) f(x) = x3 − 6x2 − 15x + 4 (a) Find the interval on which

kozerog [31]

Answer:

a) The function, f(x) is increasing at the intervals (x < -1.45) and (x > 3.45)

Written in interval form

(-∞, -1.45) and (3.45, ∞)

- The function, f(x) is decreasing at the interval (-1.45 < x < 3.45)

(-1.45, 3.45)

b) Local minimum value of f(x) = -78.1, occurring at x = 3.45

Local maximum value of f(x) = 10.1, occurring at x = -1.45

c) Inflection point = (x, y) = (1, -16)

Interval where the function is concave up

= (x > 1), written in interval form, (1, ∞)

Interval where the function is concave down

= (x < 1), written in interval form, (-∞, 1)

Step-by-step explanation:

f(x) = x³ - 6x² - 15x + 4

a) Find the interval on which f is increasing.

A function is said to be increasing in any interval where f'(x) > 0

f(x) = x³ - 6x² - 15x + 4

f'(x) = 3x² - 6x - 15

the function is increasing at the points where

f'(x) = 3x² - 6x - 15 > 0

x² - 2x - 5 > 0

(x - 3.45)(x + 1.45) > 0

we then do the inequality check to see which intervals where f'(x) is greater than 0

Function | x < -1.45 | -1.45 < x < 3.45 | x > 3.45

(x - 3.45) | negative | negative | positive

(x + 1.45) | negative | positive | positive

(x - 3.45)(x + 1.45) | +ve | -ve | +ve

So, the function (x - 3.45)(x + 1.45) is positive (+ve) at the intervals (x < -1.45) and (x > 3.45).

Hence, the function, f(x) is increasing at the intervals (x < -1.45) and (x > 3.45)

Find the interval on which f is decreasing.

At the interval where f(x) is decreasing, f'(x) < 0

from above,

f'(x) = 3x² - 6x - 15

the function is decreasing at the points where

f'(x) = 3x² - 6x - 15 < 0

x² - 2x - 5 < 0

(x - 3.45)(x + 1.45) < 0

With the similar inequality check for where f'(x) is less than 0

Function | x < -1.45 | -1.45 < x < 3.45 | x > 3.45

(x - 3.45) | negative | negative | positive

(x + 1.45) | negative | positive | positive

(x - 3.45)(x + 1.45) | +ve | -ve | +ve

Hence, the function, f(x) is decreasing at the intervals (-1.45 < x < 3.45)

b) Find the local minimum and maximum values of f.

For the local maximum and minimum points,

f'(x) = 0

but f"(x) < 0 for a local maximum

And f"(x) > 0 for a local minimum

From (a) above

f'(x) = 3x² - 6x - 15

f'(x) = 3x² - 6x - 15 = 0

(x - 3.45)(x + 1.45) = 0

x = 3.45 or x = -1.45

To now investigate the points that corresponds to a minimum and a maximum point, we need f"(x)

f"(x) = 6x - 6

At x = -1.45,

f"(x) = (6×-1.45) - 6 = -14.7 < 0

Hence, x = -1.45 corresponds to a maximum point

At x = 3.45

f"(x) = (6×3.45) - 6 = 14.7 > 0

Hence, x = 3.45 corresponds to a minimum point.

So, at minimum point, x = 3.45

f(x) = x³ - 6x² - 15x + 4

f(3.45) = 3.45³ - 6(3.45²) - 15(3.45) + 4

= -78.101375 = -78.1

At maximum point, x = -1.45

f(x) = x³ - 6x² - 15x + 4

f(-1.45) = (-1.45)³ - 6(-1.45)² - 15(-1.45) + 4

= 10.086375 = 10.1

c) Find the inflection point.

The inflection point is the point where the curve changes from concave up to concave down and vice versa.

This occurs at the point f"(x) = 0

f(x) = x³ - 6x² - 15x + 4

f'(x) = 3x² - 6x - 15

f"(x) = 6x - 6

At inflection point, f"(x) = 0

f"(x) = 6x - 6 = 0

6x = 6

x = 1

At this point where x = 1, f(x) will be

f(x) = x³ - 6x² - 15x + 4

f(1) = 1³ - 6(1²) - 15(1) + 4 = -16

Hence, the inflection point is at (x, y) = (1, -16)

- Find the interval on which f is concave up.

The curve is said to be concave up when on a given interval, the graph of the function always lies above its tangent lines on that interval. In other words, if you draw a tangent line at any given point, then the graph seems to curve upwards, away from the line.

At the interval where the curve is concave up, f"(x) > 0

f"(x) = 6x - 6 > 0

6x > 6

x > 1

- Find the interval on which f is concave down.

A curve/function is said to be concave down on an interval if, on that interval, the graph of the function always lies below its tangent lines on that interval. That is the graph seems to curve downwards, away from its tangent line at any given point.

At the interval where the curve is concave down, f"(x) < 0

f"(x) = 6x - 6 < 0

6x < 6

x < 1

Hope this Helps!!!

5 0

3 years ago

I have no idea how to do this, pls help. Question in the picture. Please show your work. Thanks!

geniusboy [140]

Answer:

C

Step-by-step explanation:

This is a stem and leaf plot. If you don't know what a stem and leaf plot is, try searching it before coming back and viewing the solution. I also see an "example" button. It might help to hit that too.

First, we sort the list of numbers. Here is what we get:

64, 66, 67, 68, 69, 74, 75, 76, 78, 79

Here, the stems are the tens digits and the leaves are the ones digits.

Therefore, for the stem 6, the leaves are:

4, 6, 7, 8, 9

For the stem 7, the leaves are:

4, 5, 6, 8, 9

The answer, I believe, is C

4 0

3 years ago