How to answer this question?

A 4.2 kg parachutist is moving straight downward with a speed of 3.85 m/s

statuscvo [17]

Kinetic energy= .5 x m x v^2
KE=.5 x 4.2 x 3.85^2
KE=31.13

4 0

3 years ago

A bicycile traves with an average velocty 15km/h north for 20min what is his displasment

Mila [183]

Answer:

5000 m equivalent to 5 Km

Explanation:

Average velocity = $\frac{Displacement}{Time}$

so, Displacement =Average velocity × time

We should convert Km/h to m/s so Km/h ⇒ $\frac{1000}{60*60}$ m/s, also convert time to second so, 20min ⇒(20* 60)seconds

Displacement = (15 × $\frac{1000}{60*60}$ ) × (20×60) =5000m OR 5Km

6 0

2 years ago

Carbon is allowed to diffuse through a steel plate 11 mm thick. The concentrations of carbon at the two faces are 0.88 and 0.41

Serhud [2]

Answer:

The temperature is 2584.5 K

Explanation:

Given:

Activation energy $Q = 80000$ $\frac{J}{mol}$

Preexponential $D= 6.2 \times 10^{-7}$ $\frac{m^{2} }{s}$

Diffusion flux $J = 6.4 \times 10^{-10}$ $\frac{kg}{m^{2} s}$

Thickness of plate $\Delta x = 11 \times 10^{-3}$ m

Concentration of carbon at two faces $\Delta C = (0.88 - 0.41 ) = 0.47$ $\frac{kg}{m^{3} }$

From the formula of temperature in terms of diffusion flux,

$T = (\frac{Q}{R} ) \frac{1}{\ln (\frac{D\Delta C}{J\Delta x} )}$

Where $R =$ 8.314 $\frac{J}{mol.K}$ ( gas constant )

Put the values and find the temperature,

$T = (\frac{80000}{8.314} ) \frac{1}{\ln (\frac{6.2 \times 10^{-7} \times 0.47 }{6.4 \times 10^{-10}\times 11 \times 10^{-3} } )}$

$T = 2584.5$ K

Therefore, the temperature is 2584.5 K

8 0

3 years ago

Consider the following three statements: For any electromagnetic radiation, the product of the wavelength and the frequency is a

boyakko [2]

Answer:

The correct answer is B. Statements (i) and (ii) are true.

Explanation:

Fisrt statement:

Electromagnetic radiation such as wave, wavelength λ and oscillation frequency ν are related by a constant, the speed of light. The equation is given by:

$c= \lambda \nu$

So the first statement is true.

Second statement:

$c=\lambda \nu\\c= 3.0 A \times 1.0\times 10^{18} Hz\\c= 3.0\times 10^{-10} m \times 1.0\times 10^{18} s^{-1}\\c=3\times 10^8 \frac{m}{s}$

The value of c in the vacuum is 3×10⁸ m/s. Hence, the second statement is true.

Third statement:

The speed of any electromagnetic radiation is constant regardless the type of radiation.

Hence, the third statement is false.

8 0

3 years ago

Water can dissolve almost anything in the universe

Elodia [21]

Answer:

No, its not possible for water to dissolve almost anything in the universe.

Explanation:

Solubility of a solute defines the ability of that solute to dissolve in a given solvent. It is defined as the maximum amount of solute dissolved in a solvent at equilibrium. The solution which results from dissolving this maximum amount is called a saturated solution, and one it has been reached, no more solute can be dissolved in it.

Different substances in the universe have diffferent solubilities in water, some very high (soluble) (eg. sugar and salt) and some very low (insoluble) (eg plastics). The substances that are able to form bonds with water (Hydrogen or Ionic) are more soluble than those who are not able to do so.

5 0

3 years ago