a car is running with the velocity of 72 km/h . what will be it's velocity after 5 seconds if it's acceleration -2 m/s² ?

7) You think you have found a diamond. Its mass is 5.28 g and its volume is 2 cm3. Calculate the density

lesya [120]

Answer:

$\boxed {\tt d=2.64 \ g/cm^3}$

$\boxed {\tt Not \ a \ diamond}$

Explanation:

Density can be found by dividing the mass by the volume.

$d=\frac{m}{v}$

The mass is 5.28 grams and the volume is 2 cubic centimeters.

$m=5.28 \ g\\v= 2 \ cm^3$

Substitute the values into the formula.

$d=\frac{5.28 \ g }{2 \ cm^3}$

Divide.

$d=2.64 \ g/c^3$

The density of the unknown substance is 2.64 grams per cubic centimeter.

The density of a diamond is about 3.5 grams per cubic centimeter. Since 2.64 is not equal to 3.5, the unknown substance is not a diamond.

6 0

4 years ago

A steel wire of length 1.5 m and diameter 1 mm is joined to an aluminum wire of identical dimensions to make a composite wire of

Anarel [89]

Answer:

1.805 mm

Explanation:

Extension in the steel wire = WL_{steel}/AE_{steel}

Extension in the aluminium wire = WL_{Al}/AE_{Al}

Total extension = W/A * (L_{steel}/E_{steel} + L_{Al}/E_{Al})

we have:

W = mg

W = 5 × 9.8

W = 49 N

Area A = π/4 × (0.001)²

= 7.85398 × 10 ⁻⁷ m²

Total extension = W/A * (L_{steel}/E_{steel} + L_{Al}/E_{Al})

Total extension = 49/ 7.85398 × 10 ⁻⁷ ( (1.5/ 200×10⁹) + 1.5/ 70×10⁹))

Total extension = 0.0018048

Total extension = 1.805 mm

Thus, the total extension = the resulting change in the length of this composite wire = 1.805 mm

4 0

3 years ago

Intersystem crossing is:

Semenov [28]

An intersystem crossing (ISC) is a non-radiative process that involves the transition between two electronic states with different spin multiplicity. That is, when an electron is excited in a molecule in a basal singlet state (either by absorption or radiation) into a state of greater energy, an excited singlet or triplet state can be obtained.

Therefore, ISC is understood as an a non radio active transition between states with different spin multiplicity.

Correct answer is C: a radiative transition between states with the same spin.

8 0

4 years ago

A bowling ball reaches a speed of 10 m/s on the first roll, on the second roll it reaches a speed of 8 m/s. Which roll had the m

Archy [21]

Kinetic energy is related to an object's mass and velocity. The greater the velocity, the greater its kinetic energy will be if the mass remains constant. (so, the 10 m/s one)

8 0

3 years ago

A physics student with too much free time drops a watermelon from a roof of a building, hears the sound of the watermelon going

tatiyna

Answer:

28.6260196842 m

Explanation:

Let h be the height of the building

t = Time taken by the watermelon to fall to the ground

Time taken to hear the sound is 2.5 seconds

Time taken by the sound to travel the height of the cliff = 2.5-t

Speed of sound in air = 340 m/s

For the watermelon falling

$s=ut+\frac{1}{2}at^2\\\Rightarrow h=0t+\frac{1}{2}\times 9.81\times t^2\\\Rightarrow h=\frac{1}{2}\times 9.81\times t^2$

For the sound

Distance = Speed × Time

$\text{Distance}=340\times (2.5-t)$

Here, distance traveled by the stone and sound is equal

$\frac{1}{2}\times 9.81\times t^2=340\times (2.5-t)\\\Rightarrow 4.905t^2=340\times (2.5-t)\\\Rightarrow t^2=\frac{340}{4.905}(2.5-t)\\\Rightarrow t^2+69.3170234455t-173.292558614=0$

$t=\frac{-69.31702\dots +\sqrt{69.31702\dots ^2-4\cdot \:1\cdot \left(-173.29255\dots \right)}}{2\cdot \:1},\:t=\frac{-69.31702\dots -\sqrt{69.31702\dots ^2-4\cdot \:1\cdot \left(-173.29255\dots \right)}}{2\cdot \:1}\\\Rightarrow t=2.4158\ s\ or\ -71\ seconds$

The time taken to fall down is 2.4158 seconds

$h=\frac{1}{2}\times 9.81\times 2.4158^2=28.6260196842\ m$

Height of the buidling is 28.6260196842 m

7 0

3 years ago

a car is running with the velocity of 72 km/h . what will be it's velocity after 5 seconds if it's acceleration -2 m/s² ?​

a car is running with the velocity of 72 km/h . what will be it's velocity after 5 seconds if it's acceleration -2 m/s² ?