Humanity is faced by many challenges and problems.

When momentum is conserved it is called _____. (multiple choice)

Klio2033 [76]

Answer:

Based off the word "conserved" I would say

A. Conservation of Momentum.

Explanation:

8 0

3 years ago

72.0-kg person pushes on a small doorknob with a force of 5.00 N perpendicular to the surface of the door. The doorknob is locat

expeople1 [14]

Answer: $I=2 kg-m^2$

Explanation:

Given

mass $m=72 kg$

Force $F=5 N$

door knob is located at a distance of r=0.8 m from axis

Angular acceleration of door $\alpha =2 rad/s^2$

Torque $T=I\alpha =F\times r$

where I=moment of inertia

$5\times 0.8=I\times 2$

$I=2 kg-m^2$

4 0

3 years ago

What is the electric potential v due to the nucleus of hydrogen at a distance of 5.292×10−11 m ?

viktelen [127]

Answer: 27.21 V

Explanation:

The electric potential $V_{E}$ due to a point charge is expressed as:

$V_{E}=k\frac{q}{r}$

Where:

$k=9(10)^{9}\frac{Nm^{2}}{C^{2}}$ is the electric constant

$q=1.6(10)^{-19}C$ is the electric charge of the hydrogen nucleus, which is positive

$r=5.292(10)^{-11}m$ is the distance

Rewritting the equation with the known values:

$V_{E}=9(10)^{9}\frac{Nm^{2}}{C^{2}}\frac{1.6(10)^{-19}C}{5.292(10)^{-11}m}$

Finally:

$V_{E}=27.21 V$

5 0

3 years ago

Our Sun shines bright with a luminosity of 3.828 x 1025 Watt. Her energies

kifflom [539]

Answer:

a) E = 1.58 10²¹ J , b) Oil = 4,236 107 liter , e) T = 54.3 C

Explanation:

a) To calculate the energy that reaches Earth, let us combine that the power emitted by the Sun is distributed uniformly on a spherical surface

I = P / A

A = 4π r²

in this case the radius of the sphere is the distance from the Sun to Earth r = 1.5 10¹¹ m

I = P / A

I = P / 4π r²

let's calculate

I = 3,828 10²⁵/4 pi (1.5 10¹¹)²

I = 1.3539 10²W / m² = 135.4 W / m2

the energy that reaches the disk of the Earth is

E = I A

the area of a disc

A = π r²

E = I π r²

where r is the radius of the Earth 6.37 10⁶ m

E = 135.4 π(6.37 10⁶)

E = 1,726 10¹⁶ W

This is the energy per unit of time that reaches Earth

t = 1 dai (24h / 1day) (3600s / 1h) = 86400 s

E = 1,826 10¹⁶ 86400

E = 1.58 10²¹ J

b) for this part we can use a direct proportions rule

Oil = 1.58 10²¹ (1 / 37.3 10⁶)

Oil = 4,236 10⁷ liter

c) to silence the surface temperature of the Earth we use the Stefan-Bolztman Law

P = σ A e T⁴

T = $\sqrt[4]{P/Ae}$

nos indicate the refect, therefore the amount of absorbencies

P_absorbed = 0.7 P

let's calculate

T = REA (0.7 1.58 1021 / [pi (6.37 106) 2 1)

T = RER (8,676 106)

T = 54.3 C

b) Among the other factors that must be taken into account is the greenhouse effect, due to the absorption of gases from the atmosphere

4 0

3 years ago

The ms = 0.5645 and mk=0.1113 for a 30 N box on level ground. What level force is needed to start the box moving

nevsk [136]

Answer:

16.935 N

Explanation:

In order to make the box start moving, the level force applied on the box (F) must be greater than the force of static friction that keeps the box at rest, which is equal to

$F_f = \mu_s (mg)$

where

$\mu_s = 0.5645$ is the coefficient of static friction

(mg) = 30 N is the weight of the box

Therefore, the condition for F must be:

$F \geq F_f\\F \geq \mu_k (mg)=(0.5645)(30 N)=16.935 N$

So, the applied force must be greater than this value.

3 0

3 years ago