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3 years ago

Which of the following represents a system that is completely open?

Physics

2 answers:

Bezzdna [24]3 years ago

6 0

Answer:

I choose D

Explanation:

because all of the other ones are most likey to be close/coverd

fredd [130]3 years ago

5 0

<span>The correct answer is D. The system that is completely open of the available answers would be an open pot of boiling water. This is due to the fact that an open system is defined as one in which energy or mass can be put out into or taken from the environment. Therefore, the evaporation of water due to the heat when a pot is boiling would be an example of lost energy, and therefore this is an open system.</span>

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A shopper pushes a grocery cart 20.0 m at constant speed on level ground, against a 35.0 N frictional force. He pushes in a dire

svp [43]

Answer:

(A). The work done on the cart by the friction is -700 J.

(B). The work done on the cart by the gravitational force is 0 J.

(C). The work done on the cart by the shopper is 700 J.

(D). The force the shopper exerts 38.61 N.

(E). The total work done on the cart is zero.

Explanation:

Given that,

Distance = 20.0 m

Frictional force = 35.0 N

Angle = 25.0°

(A). We need to calculate the work done on the cart by the friction

Using formula of work done

$W_{fr} = -F\cdot d$

Where, F = force

d = distance

Put the value into the formula

$W_{fr}=-35.0\times20$

$W_{fr}=−700\ J$

(B). The work done by the gravity is perpendicular to the direction of the motion

We need to calculate the work done on the cart by the gravitational force

Using formula of work done

$W=fd\cos\theta$

Put the value into the formula

$W=35.0\times20\cos90$

$W=0\ J$

(C). We need to calculate the work done on the cart by the shopper

Using formula of work done

$W_{sh}=W_{net}-W_{fr}$

Put the value into the formula

$W_{sh}=0-(-700)$

$W_{sh}=700\ J$

(D). We need to calculate the force the shopper exerts

Using formula of force

$F_{sh}=\dfrac{W_{fr}}{d\cos\theta}$

Put the value into the formula

$F_{sh}=\dfrac{700}{20\cos25}$

$F_{sh}=38.61\ N$

(E). We need to calculate the total work done on the cart

Using formula of work done

$W_{cart}=W_{fr}+W_{sh}$

Put the value into the formula

$W_{cart}=700-(-700)$

$W_{cart}=0\ J$

Hence, (A). The work done on the cart by the friction is -700 J.

(B). The work done on the cart by the gravitational force is 0 J.

(C). The work done on the cart by the shopper is 700 J.

(D). The force the shopper exerts 38.61 N.

(E). The total work done on the cart is zero.

6 0

3 years ago

An emf is induced by rotating a 1060 turn, 20.0 cm diameter coil in the Earth's 5.25 ✕ 10−5 T magnetic field. What average emf (

lara31 [8.8K]

Answer:

The average emf induced in the coil is 175 mV

Explanation:

Given;

number of turns of the coil, N = 1060 turns

diameter of the coil, d = 20.0 cm = 0.2 m

magnitude of the magnetic field, B = 5.25 x 10⁻⁵ T

duration of change in field, t = 10 ms = 10 x 10⁻³ s

The average emf induced in the coil is given by;

$E = N\frac{\delta \phi}{dt} \\\\E = N\frac{\delta B}{\delta t}A$

where;

A is the area of the coil

A = πr²

r is the radius of the coil = 0.2 /2 = 0.1 m

A = π(0.1)² = 0.03142 m²

$E = \frac{NBA}{t} \\\\E = \frac{1060*5.25*10^{-5}*0.03142}{10*10^{-3}} \\\\E = 0.175 \ V\\\\E = 175 \ mV$

Therefore, the average emf induced in the coil is 175 mV

3 0

3 years ago

A bicyclist passing through a city accelerates after he passes the sign post marking the city limits at x=0. His acceleration is

Anni [7]

Answer:

A. 24 m, 14 m/s

B. 8.0 m

Explanation:

Given:

x₀ = 6.0 m

v₀ = 4.0 m/s

a = 5.0 m/s²

t = 2.0 s

A. Find: x and v

x = x₀ + v₀ t + ½ at²

x = (6.0 m) + (4.0 m/s) (2.0 s) + ½ (5.0 m/s²) (2.0 m/s)²

x = 24 m

v = at + v₀

v = (5.0 m/s²) (2.0 s) + (4.0 m/s)

v = 14 m/s

B. Find x when v = 6.0 m/s.

v² = v₀² + 2a (x − x₀)

(6.0 m/s)² = (4.0 m/s)² + 2 (5.0 m/s²) (x − 6.0 m)

x = 8.0 m

8 0

3 years ago

Which structures allow for the removal of wastes from the developing fetus?

castortr0y [4]

The fetus relies upon its mother as it develops. These are some of the things it needs:

<span>protection against knock and bumps, and temperature changes oxygen for respiration nutrients (food and water) </span>

The developing fetus also needs its waste substances removing.

The fetus is protected by the uterus and the amniotic fluid, a liquid contained in a bag called the amnion.

5 0

4 years ago

G the density of an object equals its mass divided by its volume. the mass of earth is 6 × 1024 kg and its radius is 4 × 103 mil

lorasvet [3.4K]

Assuming the earth and the sun to be perfect spheres,

Volume of the sphere = 4/3 * pi * (r**3)

Volume of the earth = 4/3 * pi * ((4000*1.609 km)**3) = 1.116 E 12 km3

Volume of the Sun= 4/3 * pi * ((7 E 5 km)**3) = 1.436 E 18 km3

Density = mass /volume

Density of earth = 6 E 24 kg / 1.116 E 12 km3 = 5.376 E 12 [kg/km3]

Density of Sun= 2 E 30 kg / 1.436 E 18 km3 = 1.392 E 12 [kg/km3]

Density of earth / Density of Sun =

5.376 E 12 [kg/km3] / 1.392 E 12 [kg/km3] = 3.86

8 0

4 years ago

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