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Harlamova29_29 [7]
4 years ago
12

A 58.1 kg wood board is resting on very smooth ice in the middle of a frozen lake. A 48.3 kg boy stands at one end of the board.

He walks from one end of the board to the other end with a velocity of 1.69 m/s relative to the ice in the positive direction. What is the velocity of the board relative to the ice? -1.69m/s
Physics
1 answer:
VLD [36.1K]4 years ago
4 0

Answer:

V = 1.41 m /s

Explanation:

Movement in both wood board and boy is created by internal forces . No horizontal external force acts on them . So conservation of momentum will apply on both of them for movement in horizontal direction.

Mass of wood board x velocity = mass of boy x velocity

58.1 x V = 48.3 x 1.69

V = 1.41 m /s

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73 Newton is the correct answer
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Older railroad tracks in the U.S. are made of 12-m-long pieces of steel. When the tracks are laid, gaps are left between section
____ [38]

Answer: ∆L = 0.49cm ≈ 0.50cm

Therefore there should be 0.5 cm gap between each piece of steel.

Explanation:

Thermal expansion of steel is the increase in size of steel as a result of increased temperature. It can be represented by the mathematical expression:

∆L = L(k)∆T .....1

Where;

∆L is the change in length

L is the initial length

∆T is the change in temperature

k is the specific Linear expansion coefficient.

Given;

L = 12m

∆T = 50°C - 16°C = 34°C

k (for steel) = 1.2 × 10^-6 /C

Substituting the values into the equation 1

∆L = 12 × 34 × 12×10^-6

∆L = 4896 × 10^-6 m

∆L = 0.49cm ≈ 0.50cm

Therefore there should be 0.5 cm gap between each piece of steel.

6 0
3 years ago
Read 2 more answers
Two electrons exert a force of repulsion of 1.2 N on each other. How far apart are they? The elementary charge is 1.602 × 10−19
aleksandr82 [10.1K]

Answer:

The answer to your question is distance between these electrons

                                                   = 1.386 x 10⁻¹⁴ m

Explanation:

Data

Force = F = 1.2 N

distance = d = ?

charge = q₁ = q₂ = 1.602 x 10⁻¹⁹ C

K = 8.987 x 10⁹ Nm²/C²

Formula

-To solve this problem use the Coulomb's equation

  F = kq₁q₂ / r²

-Solve for r²

  r² = kq₁q₂ / F

-Substitution

  r² = (8.987 x 10⁹)(1.602 x 10⁻¹⁹)(1.602 x 10⁻¹⁹) / 1.2

- Simplification

  r² = 2.306 x 10⁻²⁸ / 1.2

  r² = 1.922 x 10⁻²⁸

-Result

  r = 1.386 x 10⁻¹⁴ m

7 0
4 years ago
A ball is released from rest at a height of 10 m and falls freely to the
ElenaW [278]

Answer:

The new kinetic energy would be 16 times greater than before.

Explanation:

Kinetic energy is found using this formula:

  • KE = 1/2mv²
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We can see that kinetic energy is directly proportional to the square of the velocity, meaning that if the speed was increased by 4 times, then the kinetic energy would get increased by a factor of 16.

The velocity just before the ball hits the ground can be found by the equation:

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Let's substitute h = 10 m and h = 40 m into this formula.

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We can see that the velocity increases by a factor of 4 (10 m → 40 m).

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Suppose high tide is at midnight, the water level at midnight is 3 m, and the water level at low tide is 0.5 m. Assuming the nex
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We have that the time, to the nearest minute, when the water level is at 1.125 m for the second time after midnight is

t=10.0hours

From the Question we are told that

Maximum height h_{max}=3m

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Time for  next high tide will occurT=12 hours =>720 min

Generally Average Height

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Therefore determine Amplitude to be

A=h_{max}=j_{avg}\\\\A=3-1.75\\\\A=1.25

Generally, the equation for Time is mathematically given by

At t=0

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Hence the Time at T=1.125 is

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For more information on this visit

brainly.com/question/22361343

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