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Orlov [11]
3 years ago
12

A girl coasts down a hill on a sled, reaching

Physics
1 answer:
Simora [160]3 years ago
8 0

The sled travels a distance of 60.2 m before coming to rest.

The girl  reaches the ground with a speed <em>u</em>. She then travels forward on the hard icy snow, which has a coefficient of kinetic friction \mu _k . She comes to rest after travelling a distance <em>s</em> on the ground, due to the friction between the sled and the ground.

If the force of friction is <em>f</em> , the mass of the girl and the sled is <em>m</em> and the acceleration due to gravity is <em>g</em>, then,

f=\mu_kmg    .......(1)

This force exerts a decelerating force on the sled. If the deceleration of the sled is <em>a</em>, then,

f=ma   .......(2)

From equations (1) and (2),

f=\mu_kmg=-ma\\ a=-\mu_kg......(3)

Substitute 0.038 for  \mu _k and 9.81 m/s²for g.

a=-\mu_kg\\ =-(0.038)(9.81m/s^2)\\ =-0.3728m/s^2

Since the girl comes to rest, its final velocity is 0. Substitute 6.7 m/s for <em>u</em> and -0.3728m/s² for <em>a</em> in the equation of motion

v^2=u^2+2as

Solve for <em>s</em>.

v^2=u^2+2as\\ (0m/s)^2=(6.7m/s)^2+2(-0.3728m/s^2)s\\ s=\frac{(6.7m/s)^2}{2(0.3728m/s^2)} \\ =60.2m

Thus, the girl travels a distance of 60.2 m before coming to rest.

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2.7%,Almost three percent of adolescents

Explanation:

The two most common eating disorders are anorexia nervosa and bulimia what percentage of American adolescents have experienced anorexia nervosa or bulimia

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On what factors does critical velocity depend on
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A glass rod and a steel rod are of equal length at 0C. At 100C they differ in length by
NeX [460]

The given lengths at 0 °C are 2.5 m

Let l₀ be the given lengths of the glass and steel rods at 0 °C. Let l and l' be the lengths of the glass and steel rods at 100 °C respectively.

From our expression for linear expansivity,

l = l₀ + l₀αΔθ where α = linear expansivity of glass = 0.000008/°C and Δθ = temperature change = θ - θ' where θ = 100 °C and θ' = 0 °C. So, Δθ = 100 °C - 0 °C = 100 °C.

Also,

l' = l₀ + l₀α'Δθ where α' = linear expansivity of steel = 0.000012/°C and Δθ = temperature change = θ - θ' where θ = 100 °C and θ' = 0 °C. So, Δθ = 100 °C - 0 °C = 100 °C.

Since the difference in their lengths at 100 °C = 0.001 m, we have that

l - l' = l₀ + l₀αΔθ - (l₀ + l₀α'Δθ)

l - l' = l₀ + l₀αΔθ - l₀ - l₀α'Δθ)

l - l' = l₀αΔθ - l₀α'Δθ

l - l' = l₀(α- α')Δθ

Making l₀ subject of the formula, we have

l₀ = (l - l')/[(α- α')Δθ]

Substituting the values of the variables into the equation, we have

l₀ = (l - l')/[(α- α')Δθ]

l₀ = 0.001 m/[(0.000008/°C - 0.000012/°C)100 °C.]

l₀ = 0.001 m/[(-0.000004/°C)100 °C.]

l₀ = 0.001 m/-0.0004

l₀ = -2.5 m

Neglecting the negative sign,

l₀ = 2.5 m

So, the given lengths at 0 °C are 2.5 m

Learn more about linear expansion here:

brainly.com/question/14089545

6 0
2 years ago
. A dog walks 14 m to the east and then 20 m back to the west. What is the distance? What is the displacement?​
Crank

Answer:

Hi...

14-20=-6...displacement

14+20=34...distance

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