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Mandarinka [93]

3 years ago

13

Light traveling through the air strikes the surface of the four materials below. Which material reflects light but does not refr

act it?
A) Diamond
B) Water Droplets
C) Prism
D) Metal Spoon

2 answers:

aliina [53]3 years ago

7 0

I could of sworn it was d metal spoon

Marizza181 [45]3 years ago

4 0

I think it is d am i right

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The length of a rectangular sheet of metal decreases by 34.5 cm. Its width decreases proportionally. If the sheets original widt

devlian [24]

The original width was 94.71 cm
<span>The area decreased 33.1% </span>

<span>The equation for the final size is </span>
<span>2X^2 = 1.2 m^2 </span>
<span>X^2 - 0.6 m^2 </span>
<span>X^2 = 10000 * .6 cm </span>
<span>X = 77.46 cm (this is the width) </span>

<span>The length is 2 * 77.46 = 154.92 cm </span>

<span>The original length was 154.92 + 34.5 = 189.42 cm </span>
<span>The original width was 189.42 / 2 = 94.71 cm </span>

<span>The original area was 94.71 * 189.92 = 17939.9 cm^2 </span>
<span>The new area is 79.46 * 154.92 = 12000.1 cm^2 </span>

<span>The difference between the original and current area is 17939.9 - 12000.1 = 5939.86 cm^2 </span>

<span>The percentage the area decreased is 5939.86 ' 17939.9 = 33.1%</span>

6 0

3 years ago

How many times does a human heart beat during a person’s lifetime? How many gallons of blood does it pump? (Estimate that the he

Nostrana [21]

Answer: The heart pumps 124.2 billion cm³ of blood in a lifetime

Explanation:

as an adult the pulse rate average must be around 72 beats per minute.

The heart beats about 103,680 times in a day.

There are 365 days in a year

number of heart beat in a year = 365 days x 103,680 = 37,843,200 beats in a year

For every the heart pumps 50cm³ of blood,

Hence,

Amount of blood pump in a year = 50 x 37,843,200 = 1,892,160,000cm³ of blood pumped in a year.

Using the estimated lifespan average an individual is 69 years

So in a life time,

The human heart pumps = 1,892,160,000 x 69 years = 124,200,000,000

If the heart pumps 50cm³ of blood per beat, the heart pumps a total of 130,559,040,000 cm³ (130.6 billion cm³) of blood in a LIFETIME.

3 0

3 years ago

The spring of a toy car is wound by pushing the car

Zepler [3.9K]

The elastic potential energy stored in the car's spring during the process is 3.75 J

<h3>Determination of the spring constant</h3>

From the question given above, the following data were obtained:

Force (F) = 15 N

Extention (e) = 0.5 m

Spring constant (K) =?

K = F/e

K = 15 / 0.5

K = 30 N/m

<h3>Determination of the potential energy</h3>

Spring constant (K) = 30 N/m

Extention (e) = 0.5 m

Potential energy (PE) =?

PE = ½Ke²

PE = ½ × 30 × 0.5²

PE = 15 × 0.25

PE = 3.75 J

Therefore, the elastic potential energy stored in the car's spring during the process is 3.75 J

Learn more about energy stored in spring:

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7 0

2 years ago

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How do birds manage to fly without flapping their wings?

nignag [31]

It's called gliding.
So, they will get up high and collect their balance and be nice and steady. Then, they can spread their wings out and glide. The wind will carry them from their.
How do we manage to stand without constantly walking? It's the same exact thing.

3 0

3 years ago

Students are going to conduct an experiment to study the effect of a net force applied to an object on the object’s motion. In e

Ronch [10]

Answer:

A. velocity and time

Explanation:

A force can be define as an agent which has the capacity to change the state of an object. It can either increase the velocity of a body, change its direction of motion or cause a moving object to come to rest.

From Newton's second law of motion;

F = ma

where F is the force on the object, m is the mass of the object and a is the acceleration of the object. The unit of force is kgm/ $s^{2}$ or Newtons.

a = $\frac{change in velocity}{change in time}$

In the given question, apart from the mass of the object which is constant, the students should take the measurements of the velocity and time in each trial so as to calculate the required acceleration.

7 0

3 years ago

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