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3 years ago

How fast must a 70 kg student be running to have a kinetic energy of 568 J?!

Physics

1 answer:

Dmitry [639]3 years ago

4 0

Answer: 4.03 m/s

Explanation: Kinetic energy is

KE = 1/2 m v²

So we derive the equation to have v.

v = √ 2KE / m

= 2 x 568 J / 70 kg

= 16.23

= √ 16.23

= 4.03 m/s

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calculate the distance a plane flies on a 7.95 hour flight from Chicago to London. Assume a constant speed of 800.0 km/h

soldier1979 [14.2K]

Answer:

6360 km

Explanation:

Use the kinematics equation $x=v_ot+\frac{1}{2}at^2$ . We are given t = 7.95 hours and a = 0 m/s^2 (constant speed means there is no acceleration). Solve for x.

$x=(800)(7.95)+\frac{1}{2}(0)(7.95^2)\\x=6360 \ km$

4 0

3 years ago

What is the density of a block of wood with a mass of 120 g and a volume of 200 cm

creativ13 [48]

D=m/V therefore the answer is 120/200 or 0.6

7 0

3 years ago

A projectile is shot at an angle 45 degrees to the horizontalnear the surface of the earth but in the absence of air resistance.

ivann1987 [24]

Answer:

v₂ = 176.24 m/s

Explanation:

given,

angle of projectile = 45°

speed = v₁ = 150 m/s

for second trail

speed = v₂ = ?

angle of projectile = 37°

maximum height attained formula,

$H_{max}= \dfrac{v^2 sin^2(\theta)}{g}$

now,

$H_{max}= \dfrac{v_1^2 sin^2(\theta_1)}{g}$

$H_{max}= \dfrac{v_2^2 sin^2(\theta_2)}{g}$

now, equating both the equations

$\dfrac{v_2^2}{v_1^2}=\dfrac{sin^2(\theta_1)}{sin^2(\theta_2)}$

$\dfrac{v_2^2}{150^2}=\dfrac{sin^2(45^0)}{sin^2(37^0)}$

v₂² = 31061.79

v₂ = 176.24 m/s

velocity of projectile would be equal to v₂ = 176.24 m/s

8 0

3 years ago

Assume an axon has an internal diameter of 1μm and a myelin sheath 1μm thick. The internal specific resistance is 100 Ω cm. For

SpyIntel [72]

Answer:

$1.27\times 10^{12}\Omega/m$

Explanation:

We are given that

Diameter=d= $\mu m$

Thickness= $1\mu m$

Radius= $r=\frac{d}{2}=\frac{1}{2}\mu m=0.5\times 10^{-6} m$

Using $1\mu m=10^{-6} m$

Dielectric constant=8

Resistance = $R=2\times 10^5\Omega cm^2$

Internal specific resistance=r=100 ohm cm= $100\times \frac{1}{100}\Omega-m=1\Omega m$

Using 1 m=100 cm

Internal resistance per unit length= $\frac{r}{A}=\frac{1}{\pi r^2}=\frac{1}{3.14\times (0.5\times 10^{-6})^2}=1.27\times 10^{12}\Omega/m$

Using $\pi=3.14$

Internal resistance per unit length= $1.27\times 10^{12}\Omega/m$

8 0

3 years ago

When the temperature of the air is 25 degress C, the velocity of a sound wave traveling through the air is approximately

dusya [7]

Assuming an ideal gas, the speed of sound depends on temperature
only. Air is almost an ideal gas.

Assuming the temperature of 25°C in a "standard atmosphere", the
density of air is 1.1644 kg/m3, and the speed of sound is 346.13 m/s.

The velocity can't be specified, since the question gives no information
regarding the direction of the sound.

6 0

3 years ago