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3 years ago

Josie sees lightning off in the distance. A few seconds later she hears thunder. What can Josie conclude?

Physics

2 answers:

Nana76 [90]3 years ago

7 0

The answer would be choice B)

Natalka [10]3 years ago

5 0

B Light waves travel faster than sound waves

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A swimming pool is 50 ft wide and 100 ft long and its bottom is an inclined plane, the shallow end having a depth of 4 ft and th

Nina [5.8K]

Explanation:

We define force as the product of mass and acceleration.

F = ma

It means that the object has zero net force when it is in rest state or it when it has no acceleration. However in the case of liquids. just like the above mentioned case, the water is at rest but it is still exerting a pressure on the walls of the swimming pool. That pressure exerted by the liquids in their rest state is known as hydro static force.

Given Data:

Width of the pool = w = 50 ft

length of the pool = l= 100 ft

Depth of the shallow end = h(s) = 4 ft

Depth of the deep end = h(d) = 10 ft.

weight density = ρg = 62.5 lb/ft

Solution:

a) Force on a shallow end:

$F = \frac{pgwh}{2} (2x_{1}+h)$

$F = \frac{(62.5)(50)(4)}{2}(2(0)+4)$

$F = 25000 lb$

b) Force on deep end:

$F = \frac{pgwh}{2} (2x_{1}+h)$

$F = \frac{(62.5)(50)(10)}{2} (2(0)+10)$

$F = 187500 lb$

c) Force on one of the sides:

As it is mentioned in the question that the bottom of the swimming pool is an inclined plane so sum of the forces on the rectangular part and triangular part will give us the force on one of the sides of the pool.

1) Force on the Rectangular part:

$F = \frac{pg(l.h)}{2}(2(x_{1} )+ h)$

$x_{1} = 0\\h_{s} = 4ft$

$F = \frac{(62.5)(100)(2)}{2}(2(0)+4)$

$F =25000lb$

2) Force on the triangular part:

$F = \frac{pg(l.h)}{6} (3x_{1} +2h)$

here

h = h(d) - h(s)

h = 10-4

h = 6ft

$x_{1} = 4ft\\$

$F = \frac{62.5 (100)(6)}{6} (3(4)+2(6))$

$F = 150000 lb$

now add both of these forces,

F = 25000lb + 150000lb

F = 175000lb

d) Force on the bottom:

$F = \frac{pgw\sqrt{l^{2} + ((h_{d}) - h(s)) } (h_{d}+h_{s}) }{2}$

$F = \frac{62.5(50)\sqrt{100^{2}(10-4) } (10+4) }{2}$

$F = 2187937.5 lb$

7 0

3 years ago

Please help me asap

ddd [48]

Answer:

if I aint wrong it would 2nd one

8 0

3 years ago

A person is standing on and facing the front of a stationary skateboard while holding a construction brick. The mass of the pers

Inessa [10]

Answer:

v₁ = -0.8087 m / s

Explanation:

To solve this problem we can use the conservation of momentum, for this we define a system formed by the man, the skateboard and the brick, therefore the force during the separation is internal and the momentum is conserved

Initial instant. When they are united

p₀ = 0

Final moment. After throwing the brick

$p_{f}$ = (m_man + m_skate) v1 + m_brick v2

the moment is preserved

p₀ = p_{f}

0 = (m_man + m_skate) v₁ + m_brick v₂

v₁ = - $\frac{ m_{brick} }{m_{man} + m_{skate} } v_{2}$

the negative sign indicates that the two speeds are in the opposite direction

let's calculate

v₁ = - $\frac{2.5}{67 + 4.10} 23.0$

v₁ = -0.8087 m / s

6 0

3 years ago

What is a chemical substance that cannot be broken down into another substance?

Tema [17]

The answer is C. Elements

Elements cannot be broken down int simpler substances even by chemical means

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3 years ago

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When studying atoms, scientists can ignore the ______ force between charged particles that make up the atoms because it is many

Elenna [48]

Answer:

When studying atoms, scientists can ignore the intermolecular electrostatic forces between charged particles that make up the atoms because it is many millions of times smaller than other forces in the atom. Gravitational Constant Normal Fricitional

3 0

2 years ago

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