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NemiM [27]
3 years ago
10

Two trains travel toward each other on the same track, beginning 100 miles apart. One train travels at 40 miles per hour; the ot

her travels at 60 miles an hour. A bird starts flight at the same location as the faster train, flying at a speed of 90 miles per hour. When it reaches the slower train, it turns around, flying the other direction at the same speed. When it reaches the fastest train again, it turns around -- and so on. When the trains collide, how many miles the bird has flown.
Physics
2 answers:
Paladinen [302]3 years ago
7 0

D = distance between th two trains at the start of the motion = 100 miles

V = speed of the faster train towards slower train = 60 mph

v = speed of the slower train towards faster train = 40 mph

t = time taken by the two trains to collide = ?

time taken by the two trains to collide is given as

t = D/(V + v)

t = 100/(60 + 40) = 1 h

v' = speed of the bird = 90 mph

d = distance traveled by the bird

distance traveled by the bird is given as

d = v' t

d = 90 x 1

d = 90 miles

xz_007 [3.2K]3 years ago
3 0

-- One train travels at 60 mph.  The other one travels at 40 mph.  So the space between them shrinks at the rate of 100 mph.

-- They start 100 miles apart, so they meet in 1 hour.

-- The bird and the trains all start moving at the same time, and the bird keeps flying in the space between them until they meet.  That's 1 hour.

-- The bird's speed is 90 mph.  So the bird covers <em>90 miles</em> in that hour.

-- After flying at 90 mph for a whole hour without resting, we can be sure that the bird is grateful to be put out of its misery.

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julia-pushkina [17]

To solve this problem we will apply the concepts related to the Force of gravity given by Newton's second law (which defines the weight of an object) and at the same time we will apply the Hooke relation that talks about the strength of a body in a system with spring.

The extension of the spring due to the weight of the object on Earth is 0.3m, then

F_k = F_{W,E}

kx_1 = mg

The extension of the spring due to the weight of the object on Moon is a value of x_2, then

kx_2 = mg_m

Recall that gravity on the moon is a sixth of Earth's gravity.

kx_2 = m\frac{g}{6}

kx_2 = \frac{1}{6} mg

kx_2 = \frac{1}{6} kx_1

x_2 = \frac{1}{6} x_1

We have that the displacement at the earth was x_1 = 0.3m, then

x_2 = \frac{1}{6} 0.3

x_2 = 0.05m

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6 0
3 years ago
Explain the difference between speed and velocity and indicate if these are scalar or vector quantities
Natali5045456 [20]
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3 0
3 years ago
Find a parametric representation for the surface. The plane through the origin that contains the vectors i - j and j - k
boyakko [2]

Answer:

parametric representation: x = u, y = v - u ,  z = - v

Explanation:

Given vectors :

i - j ,  j - k

represent the vector equation of the plane as:

r ( u, v ) = r₀ + <em>u</em>a + vb

where:  r₀ = position vector

            u and v = real numbers

             a and b = nonparallel vectors

expressing the nonparallel vectors as :

a = i -j , b = j - k , r = ( x,y,z ) and r₀ = ( x₀, y₀, z₀ )

hence we can express vector equation of the plane as

r(u,v) = ( x₀ + u, y₀ - u + v,  z₀ - v )

Finally the parametric representation of the surface through (0,0,0) i.e. origin = 0

( x, y , z ) = ( x₀ + u,  y₀ - u + v,   z₀ - v )

x = 0 + u ,

y = 0 - u + v

z = 0 - v

∴ parametric representation: x = u, y = v - u ,  z = - v

3 0
2 years ago
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Newton's first law of motion.
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Consider the following equations of motion.
Helen [10]

A) No, the equations presented above are the product of the derivation of position and velocity when the acceleration is constant.

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B) Yes, when the acceleration is zero it is concluded that the velocity is constant, therefore they could be used to describe the position as a function of the change in velocity.

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