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3 years ago

A 53.4 kg ice skater is at rest when she throws a 0.135 kg snowball east at 15.8 m/s. What is her velocity afterwards?

Physics

1 answer:

il63 [147K]3 years ago

5 0

Answer:

Her velocity afterwards is 0.04 m/s to the west.

Explanation:

Using the conservation of momentum, we have that:

m1u1 + m2u2 = m1v1 + m2v2

Where m is the mass, u is the inicial velocity and v is the final velocity.

The inicial momentum is zero, because the ice skater and the snowball are at rest (u1 = 0 and u2 = 0)

The mass of the snowball is m1 = 0.135 kg and the final velocity is v1 = 15.8 m/s, so the momentum of the snowball is:

m1 * v1 = 0.135 * 15.8 = 2.133 kg*m/s

So from the conservation of momentum, we have that:

0 = 2.133 + m2v2

m2v2 = -2.133

The mass of the ice skater is m2 = 53.4 kg, then we have that:

53.4 * v2 = -2.133

v2 = -2.133 / 53.4 = -0.0399 m/s

Her velocity afterwards is 0.04 m/s to the west.

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Answer:

0.6 m

Explanation:

When a spring is compressed it stores potential energy. This energy is:

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Replacing:

Ep = m * g * sin(a) * d

Equating both potential energies:

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d = (1/2 * k * x^2) / (m * g * sin(a))

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3 years ago

How many 1140 nm long molecules would you have to line up end to end to stretch a distance of 158 miles?

dezoksy [38]

Answer:

221754385964.9123

Explanation:

Convert miles to nanometer

1 mile = 1.6 km

1 km = 1×10³×10³×10³×10³ nm

1 mile = 1.6×10¹² nm

So,

158 miles = 158×1.6×10¹² = 252.8×10¹² nm

Length of each molecule = 1140 nm

Number of molecules = Total length / Length of each molecule

$\text{Number of molecules}=\frac{252.8\times 10^{12}}{1140}\\\Rightarrow \text{Number of molecules}=221754385964.9123$

There are 221754385964.9123 number of molecules in a stretch of 158 miles

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3 years ago

A virtual image is formed 17.0 cm from a concave mirror having a radius of curvature of 39.0 cm. (a) Find the position of the ob

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Explanation:

Image distance, v = -17 cm (-ve for virtual image)

Radius of curvature of concave mirror, R = 39 cm

Focal length, f = -19.5 cm (-ve for a concave mirror)

(a) Using mirror's formula as :

$\dfrac{1}{v}+\dfrac{1}{u}=\dfrac{1}{f}$

$\dfrac{1}{u}=\dfrac{1}{f}-\dfrac{1}{v}$

$\dfrac{1}{u}=\dfrac{1}{-19.5}-\dfrac{1}{(-17)}$

u = 132.6 cm

So, the object is placed 132.6 cm in front of the mirror.

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$m=\dfrac{-17}{132.6}$

m = -0.128

Hence, this is the required solution.

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