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slamgirl [31]
4 years ago
12

The density of an object is how much matter it contains. a. True b. False

Physics
1 answer:
daser333 [38]4 years ago
4 0

Answer:

False

Explanation:

The density is mass divided by volume

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What is the biggest barrier to the use of renewable energy in the United States?
storchak [24]
The biggest barrier to the use of renewable energy in the United States is the  Citizen opposition to negative environmental impact.
So, the answer is B.
7 0
3 years ago
The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have st
irina [24]

Complete Question:

The elastic energy stored in your tendons can contribute up to 35 % of your energy needs when running. Sports scientists have studied the change in length of the knee extensor tendon in sprinters and nonathletes. They find (on average) that the sprinters' tendons stretch 43 mm , while nonathletes' stretch only 32 mm . The spring constant for the tendon is the same for both groups, 31 {\rm {N}/{mm}}. What is the difference in maximum stored energy between the sprinters and the nonathlethes?

Answer:

\triangle E = 12.79 J

Explanation:

Sprinters' tendons stretch, x_s = 43 mm = 0.043 m

Non athletes' stretch, x_n = 32 mm = 0.032 m

Spring constant for the two groups, k = 31 N/mm = 3100 N/m

Maximum Energy stored in the sprinter, E_s = 0.5kx_s^2

Maximum energy stored in the non athletes, E_m = 0.5kx_n^2

Difference in maximum stored energy between the sprinters and the non-athlethes:

\triangle E = E_s - E_n = 0.5k(x_s^2 - x_n^2)\\\triangle E = 0.5*3100* (0.043^2 - 0.032^2)\\\triangle E = 0.5*31000*0.000825\\\triangle E = 12.79 J

4 0
4 years ago
If a short-wave radio station broadcasts on a frequency of 9.065 megahertz (MHz), what is the wavelength of
Yakvenalex [24]

Answer:

If the radio wave is on an FM station, these are in Megahertz. A megahertz is one ... Typical radio wave frequencies are about 88~108 MHz .

Explanation:

To calculate the wavelength of a radio wave, you will be using the equation: Speed of a wave = wavelength X frequency.

Since radio waves are electromagnetic waves and travel at 2.997 X

10

8

meters/second, then you will need to know the frequency of the radio wave.

If the radio wave is on an FM station, these are in Megahertz. A megahertz is one million hertz. If the radio wave is from an AM radio station, these are in kilohertz (there are one thousand hertz in a kilohertz). Hertz are waves/second. Hertz is usually the label for the frequency of electromagnetic waves.

To conclude, to determine the wavelength of a radio wave, you take the speed and divide it by the frequency.

Typical radio wave frequencies are about

88

~

108

MHz

. The wavelength is thus typically about

3.41

×

10

9

~

2.78

×

10

9

nm

.

7 0
2 years ago
If a block of wood dropped from a tall building has attained a velocity of 78.4 m/s how long has it been falling
ryzh [129]

Gravity adds 9.8 m/s to the speed of a falling object every second.

An object dropped from 'rest' (v = 0) reaches the speed of 78.4 m/s after  falling for (78.4 / 9.8) = <em>8.0 seconds</em> .

<u>Note:</u>

In order to test this, you'd have to drop the object from a really high cell- tower, building, or helicopter.  After falling for 8 seconds and reaching a speed of 78.4 m/s, it has fallen 313.6 meters (1,029 feet) straight down.

The flat roof of the Aon Center . . . the 3rd highest building in Chicago, where I used to work when it was the Amoco Corporation Building . . . is 1,076 feet above the street.

5 0
3 years ago
Runner A is initially 6.0 km west of a flagpole and is running with a constant velocity of 9.0 km/h due east. Runner B is initia
sergejj [24]

Answer:

0.176m from the flagpole, westward.

Explanation:

Let the Eastward be the positive direction. So initially runner A is at position -6km, running with velocity of 9km/h while runner B is at position 5km running at a velocity of -8km/h. We can conduct the following equation for their distances over the same time t

s_A = -6 + 9t

s_B = 5 - 8t

When A an B meets, they are at the same position and at the same time. So

s_A = s_B

-6 +9t = 5 - 8t

17t = 5 + 6 = 11

t = 11/17 = 0.647 s

s_A = -6 + 9*0.647 = -0.176 m

So where they meet is 0.176m from the flagpole, westward.

5 0
3 years ago
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