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erastova
1 month ago
5

A bobsledder pushes her sled across horizontal snow to get it going, then jumps in. After she jumps in, the sled gradually slows

to a halt. What forces act on the sled just after she's jumped in?
a) Gravity and kinetic friction
b) Gravity and normal force
c) Gravity and the force of the push
d) Gravity, a normal force, and kinetic friction
e) Gravity, a normal force, kinetic friction, and the force of the push
Physics
1 answer:
serg [3.5K]1 month ago
3 0
d) Gravity, a normal force, and kinetic friction When the bobsledder propels her sled across the flat snow to initiate movement, once she leaps in, gravity affects the total weight of the sled including the bobsledder. As the sled advances horizontally and not vertically, a normal force is present acting upwards against gravity. As the sled travels along the flat surface and gradually stops, a kinetic friction force acts against the motion.
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This image shows the direction of the flow of water through a constricted pipe. Which of the following happens as you move from
Keith_Richards [3271]
C. The rate of water flow diminishes.
6 0
1 month ago
An infinite sheet of charge, oriented perpendicular to the x-axis, passes through x = 0. It has a surface charge density σ1 = -2
Maru [3345]

1) For x = 6.6 cm, E_x=3.47\cdot 10^6 N/C

2) For x = 6.6 cm, E_y=0

3) For x = 1.45 cm, E_x=-3.76\cdot 10^6N/C

4) For x = 1.45 cm, E_y=0

5) Surface charge density at b = 4 cm: +62.75 \mu C/m^2

6) At x = 3.34 cm, the x-component of the electric field equals zero

7) Surface charge density at a = 2.9 cm: +65.25 \mu C/m^2

8) None of these regions

Explanation:

1)

The electric field from an infinite charge sheet is perpendicular to it:

E=\frac{\sigma}{2\epsilon_0}

where

\sigma is the surface charge density

\epsilon_0=8.85\cdot 10^{-12}F/m represents vacuum permittivity

Outside the slab, the electric field behaves like that of an infinite sheet.

Consequently, the electric field at x = 6.6 cm (situated to the right of both the slab and sheet) results from the combination of the fields from both:

E=E_1+E_2=\frac{\sigma_1}{2\epsilon_0}+\frac{\sigma_2}{2\epsilon_0}

where

\sigma_1=-2.5\mu C/m^2 = -2.5\cdot 10^{-6}C/m^2\\\sigma_2=64 \muC/m^2 = 64\cdot 10^{-6}C/m^2

The field from the sheet points left (negative, inward), and the slab’s field points right (positive, outward).

Thus,

E=\frac{1}{2\epsilon_0}(\sigma_1+\sigma_2)=\frac{1}{2(8.85\cdot 10^{-12})}(-2.5\cdot 10^{-6}+64\cdot 10^{-6})=3.47\cdot 10^6 N/C

and the negative sign indicates a rightward direction.

2)

Both the sheet’s and slab’s fields are perpendicular to their surfaces, directing along the x-axis, hence there's no y-component for the total field.

<pThus, the y-component totals zero.

This happens because both the sheet and slab stretch infinitely along the y-axis. Choosing any x-axis point reveals that the y-component of the field, generated by a surface element dS of either the sheet or slab, dE_y, will be equal and opposite to the corresponding component from the opposite side, -dE_y. Thus, the combined y-direction field is always zero.

3)

This scenario resembles part 1), but the point here is

x = 1.45 cm

which lies between the sheet and the slab. The fields from both contribute leftward as the slab has a negative charge (resulting in an outward field). Thus, the total field computes to

E=E_1-E_2

Replacing with expressions from part 1), we get

E=\frac{1}{2\epsilon_0}(\sigma_1-\sigma_2)=\frac{1}{2(8.85\cdot 10^{-12})}(-2.5\cdot 10^{-6}-64\cdot 10^{-6})=-3.76\cdot 10^6N/C

where the negative illustrates a leftward direction.

4)

This portion parallels part 2). Since both fields remain perpendicular to the slab and sheet, no component exists along the y-axis, thus the electric field's y-component is zero.

5)

Notably, the slab behaves as a conductor, signifying charge mobility within it.

The net charge on the slab is positive, indicating a surplus of positive charge. With the negatively charged sheet on the left of the slab, positive charges shift towards the left slab edge (at a = 2.9 cm), while negative charges move to the right edge (at b = 4 cm).

The surface charge density per unit area of the slab is

\sigma=+64\mu C/m^2

This average denotes the surface charge density on both slab sides at points a and b:

\sigma=\frac{\sigma_a+\sigma_b}{2} (1)

Additionally, the infinite sheet at x = 0 negatively charged \sigma_1=-2.5\mu C/m^2, induces an opposite net charge on the slab's left surface, thus

\sigma_a-\sigma_b = +2.5 \mu C/m^2 (2)

Having equations (1) and (2) allows for solving the surface charge densities at a and b, yielding:

\sigma_a = +65.25 \mu C/m^2\\\sigma_b = +62.75 \mu C/m^2

6)

We aim to compute the x-component of the electric field at

x = 3.34 cm

This point lies inside the slab, bounded at

a = 2.9 cm

b = 4.0 cm

In a conducting slab, the electric field remains at zero owing to charge equilibrium; thus, the x-component thereof in the slab is zero

7)

From part 5), we determined the surface charge density at x = a = 2.9 cm is \sigma_a = +65.25 \mu C/m^2

8)

As mentioned in part 6), conductors have zero electric fields internally. Since the slab is conductive, the electric field inside remains zero; therefore, the regions where the electric field is null are

2.9 cm < x < 4 cm

Thus, the suitable answer is

"none of these regions"

Learn more about electric fields:

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The equation for the change in the position of a train (measured in units of length) is given by the following expression: x = ½
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(B) (length)/(time³) Explanation: The term x = ½ at² + bt³ should meet dimensional consistency. This means that both bt³ and ½ at² must share the same units, which are length. To find the dimension of b, we rearrange the equation: [x] = [b]*[t]³ leads to length = [b]*time³, hence [b] = length/time³.
6 0
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How long does it take to raise the temperature of the air in a good-sized living room (3.00m×5.00m×8.00m) by 10.0∘C? Note that t
Softa [3030]
The required duration is 16.1 minutes. To determine the heat needed to raise the temperature, we must calculate the following amounts, where Q represents the required heat, m stands for mass, V represents the volume, C signifies specific heat, and ΔT indicates temperature change. After substituting the provided values into the formula and calculating, the next step is determining the required time based on the formula t = Q/P, where P is given as 1500 W. Ultimately, we find that the time needed is 16.1 minutes.
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1 month ago
A good quarterback can throw a football at 27 m/s (about 60 mph). If we assume that the ball is caught at the same height from w
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Response:

The ball remained airborne for 3.896 seconds

Explanation:

Given that

g = 9.8 m/s², representing gravitational acceleration,

If the angle of launch is 45°, the horizontal range will be maximized.

Both horizontal and vertical launch velocities are equal, each equating to

v_h  =  v cos θ

v_h  =  27 × cos 45°

         = 19.09 m/s.

The duration to reach maximum height is half of the flight time.

v = u + at   ∵ v = 0 (at maximum height)

19.09 - 9.8 t₁ = 0

t₁ = 1.948 s

The total time in the air equals twice the time to reach maximum height

2 t₁ = 3.896 s

The horizontal distance covered is

D = v × t

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The ball was in the air for 3.896 seconds

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