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3 years ago

The average 8-18 year old spends how many hours per day average in front of a screen doing little physical activity

Physics

1 answer:

Ne4ueva [31]3 years ago

5 0

Nearly four hours every day, doing little to no physical activity.

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The surface of the inclined plane shown is frictionless. If F = 30 N, what is the

zhuklara [117]

Answer and Explanation:

5 0

4 years ago

Us your understanding of asexual reproduction to explain why is it important that organisms reproduce in a variety of ways.

valentina_108 [34]

The genetic material is identical in asexual reproduction- in order for organisms to be strong they need variety so if a disease comes, some of the species may be able to fight it off because of their varied genetics

5 0

3 years ago

A dielectric-filled parallel-plate capacitor has plate area A = 30.0 cm2 , plate separation d = 9.00 mm and dielectric constant

PIT_PIT [208]

Answer:

$9.96\cdot 10^{-10}J$

Explanation:

The capacitance of the parallel-plate capacitor is given by

$C=\epsilon_0 k \frac{A}{d}$

where

ϵ0 = 8.85x10-12 C2/N.m2 is the vacuum permittivity

k = 3.00 is the dielectric constant

$A=30.0 cm^2 = 30.0\cdot 10^{-4}m^2$ is the area of the plates

d = 9.00 mm = 0.009 m is the separation between the plates

Substituting,

$C=(8.85\cdot 10^{-12}F/m)(3.00 ) \frac{30.0\cdot 10^{-4} m^2}{0.009 m}=8.85\cdot 10^{-12} F$

Now we can calculate the energy of the capacitor, given by:

$U=\frac{1}{2}CV^2$

where

C is the capacitance

V = 15.0 V is the potential difference

Substituting,

$U=\frac{1}{2}(8.85\cdot 10^{-12}F)(15.0 V)^2=9.96\cdot 10^{-10}J$

4 0

3 years ago

A box of mass 20kg is pulled up an inclined plane by a force of 285N. Given that the value of the incline angle is 30 degrees an

docker41 [41]

Given :

Mass of box , m = 250 kg.

Force applied , F = 285 N.

The value of the incline angle is 30°.

the coefficient of dynamic friction is $\mu=0.72$ .

To Find :

The speed with which the box is moving with, assuming it takes 4 seconds to reach the top of the incline.

Solution :

Net force applied in box is :

$F=285 - mgsin\ \theta - \mu mg cos \ \theta\\ \\F=285-mg( sin \ \theta - \mu cos\ \theta)\\\\F=285 - 20\times 10( \dfrac{1}{2}+0.72\times \dfrac{\sqrt{3}}{2})\\\\F=60.29\ N$

Acceleration , $a=\dfrac{F}{m}=\dfrac{60.29}{20}=3.01\ m/s^2$ .

By equation of motion :

$v=u+at\\\\v=0+3.01\times 4\\\\v=12.04\ m/s$

Therefore, the speed of box is 12.04 m/s.

Hence, this is the required solution.

6 0

3 years ago

A capacitor in an LC oscillator experiences a maximum potential difference of 88V and a maximum energy of 2002 uJ. At a certain

VLD [36.1K]

Answer:

Explanation:

maximum energy of capacitor

E = 1/2 C V ²

C is capacitance of capacitor and V is potential difference

given V = 88 V

E = 2002 x 10⁻⁶ J

Putting the values

2002 x 10⁻⁶ = 1/2 x C x 88²

C = .517 x 10⁻⁶ F .

In the second case

Energy E = 125 x 10⁻⁶ J .

C = .517 x 10⁻⁶

V = ?

E = 1/2 C V ²

125 x 10⁻⁶ = 1/2 x .517 x 10⁻⁶ x V²

V² = 483.55

V = 21.98 V .

6 0

4 years ago