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3 years ago

15

A school's new pump can fill the swimming pool in 2 hours, and the old pump takes 5 hours. What is the time required in hours to

fill the pool if both pumps are used together? (Enter your answer as mixed number.)

1 answer:

Vilka [71]3 years ago

6 0

.41 hours. 2/24 • 5/24 =10/24 then 10/24= .41 hours or 24.6 minutes

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Plants make food through photosynthesis, a chemical reaction. What are the starting substances of the reaction?

vekshin1

The answer is the 4th option because they don't use oxygen, that's what they produce

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3 years ago

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An object is 1.0 cm tall and its erect image is 5.0 cm tall. what is the exact magnification?

ikadub [295]

The exact magnification of the objects is calculated by dividing the cinema. We calculate it by diving the erect image size by the object size. From the given above, we find the exact magnification by dividing 5.0 cm by 1.0 cm. Thus, the answer would be 5.

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3 years ago

Beginning 145 miles directly south of the city of Hartville, a car travels due west. If the car is travelling at a speed of 42 m

ziro4ka [17]

Answer:

The rate of change of the distance is 14.89.

Explanation:

Given that,

Distance = 145 miles

Speed of car = 42 miles/hr

Distance covered by car = 55 miles

We need to calculate the the rate of change of the distance

According to figure,

Let OA is x, and AB is y.

Now, using Pythagorean theorem

$x^2=y^2+145^2$

On differentiating

$2x\dfrac{dx}{dt}=2y\dfrac{dy}{dt}$

$\dfrac{dx}{dt}=\dfrac{y}{x}\dfrac{dy}{dt}$

$\dfrac{dx}{dt}=\dfrac{55\times42}{\sqrt{55^2+145^2}}$

$\dfrac{dx}{dt}=14.89\ miles/hr$

Hence, The rate of change of the distance is 14.89.

8 0

3 years ago

A cement block accidentally falls from rest from the ledge of a 53.0-m-high building. When the block is 14.0 m above the ground,

katrin [286]

Answer:

0.405 seconds

Explanation:

Consider the amount of time it takes the block to fall from 53 m up to 14 m above the ground; then consider the amount of time it takes the block to fall from 53 m up to 2 m above the ground.

First, d = (1/2) gt^2 or t= ( 2 d / g)^1/2

= ( 2 × 39 / 9.8)^1/2 = 2.8212 seconds

Then, to fall from 53 down to 2 meters...

d = (1/2) gt^2 or t= ( 2 d / g)^1/2

= ( 2 * 51/ 9.8 )^1/2 = 3.2262 seconds

So the amount of time it takes for the block to fall from 14 m upto 2 m above the ground

3.2262 - 2.8212 = 0.405 seconds

this is how much time there is from when the man sees the block until it hits him. Not much time...

5 0

3 years ago

The driver of a car going 96.0 km/h suddenly sees the lights of a barrier 39.0 m ahead. It takes the driver 0.75 s to apply the

arsen [322]

Answer:

21.42m/S

Explanation:

Hello!

To solve this problem we must perform the following steps.

1. Find the distance traveled from until the driver reacts, this is achieved using the equation for constant speed movement.

X1=VT

where

x= distance traveled

v=initial speed

T=time=0.75s

X1=0.75Vo

we must take into account that the total distance is the sum of the distance at which the pilot reacts (x1) and when it starts to decelerate (x2)

39=0.75Vo+X2

X2=39-0.75Vo

2. Now we use the equation that defines a movement with constant acceleration.

$Vo =\sqrt{Vf^2 - 2(a)(x2)}$

where

Vf = final speed=0m/s

Vo = Initial speed

A = acceleration =-10m/s2

X2 = displacement

now we use the ecuation of step 1

$Vo =\sqrt{Vf^2 - 2(a)(39-0.75Vo)}$

solving

$Vo =\sqrt{0 - 2(-10))(39-0.75Vo)}\\Vo^2=780-15Vo\\Vo^2+15Vo-780=0$

Now we solve the quadratic equation and find the value of Vo

the solutions are 21.42m/S, -36.41m/S

as the speed must be positive we conclude that the answer is 21.42m/S

6 0

3 years ago