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3 years ago

A young athlete has a mass of 42 kg. On a day when there is no wind she runs a 100m race in 14.2

Physics

1 answer:

Cloud [144]3 years ago

3 0

Answer:

7 m/s approx

Explanation:

Step one:

Given data

Mass m= 42kg

distance covered= 100m

time taken = 14.2 seconds

Required

The speed of the athlete

Step two:

We know that speed= distance/time

Substitute

Speed= 100/14.2

Speed= 7.04 m/s

Speed= 7 m/s approx

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alexandr1967 [171]

Answer:

a) the one with a lower orbit b) the one with a higher orbit

Explanation:

Let's consider orbital mechanics. To get an object in orbit, we need it to fall to earth parallel to the earth's surface. To understand it easily imagine a projectile thrown horizontally further and further away, at one point, the projectile hits the cannon from behind. Considering there is no wind resistance, that would be a projecile in orbit.

In other words, the circular orbits of some objects around a massive body are due to the equality between centrifugal acceleration and gravity acceleration.

$\frac{v^2}{r} = \frac{GM}{r^2}$ .

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$v = \sqrt{\frac{GM}{r} }$

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$T = 2\pi \sqrt{\frac{a^3}{GM} }$

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4 years ago

Two balls of equal size are dropped from the same height from the roof of a building. the mass of ball a is twice that of ball b

Sindrei [870]

The mass of ball a is twice the mass of ball b:
$m_a = 2 m_b$
This means that the initial potential energy of ball a ( $U_a = m_a gh=2 m_b gh$ ) is twice the potential energy of ball b ( $U_b = m_b g h$ ):
$U_a = 2 U_b$
When the two balls reach the ground, the potential energy of each ball has converted into kinetic energy (since now their altitude is h=0), because the total mechanical energy of each ball must be conserved. Therefore:
$K_a = U_a$
$K_b = U_b$
and so the kinetic energy of ball a must be twice the kinetic energy of ball b:
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3 years ago

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just olya [345]

I predict that the planet with active volcanoes will have more craters, due to the volcanic explosions, as opposed to a planet without active volcanoes.

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4 years ago

Calculate the magnitude of the electric field at one corner of a square 1.10 m on a side if the other three corners are occupied

natka813 [3]

The direction of magnetic field is south-east and the magnitude is

$23.66$ × $10^{3} N/C$ .

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To find the magnitude of the electric field use the formula

$E = kq/ r^{2}$