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3 years ago

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Dana is on a train traveling at a speed of 20 km/h. Dana walks from the front of the train to the back of the train at a speed o

f 4 km/h. What is Dana's speed relative to the ground?

1 answer:

dezoksy [38]3 years ago

5 0

Answer:

Diana's speed relative to ground is <u>16 km/h</u> in the direction of motion of train.

Explanation:

Given:

Velocity of train in forward direction is, $v_{t,g}=20\ km/h$

Here, $v_{t,g}\to \textrm{velocity of the train relative to ground.}$

Velocity of Diana relative to train in the backward direction is, $v_{D,t}=-4\ km/h$

Negative sign implies backward motion or motion opposite to the direction of train's motion. Here, Diana is walking from front of train to back. So, Diana is moving in the opposite direction.

Now, we know that, for two bodies 'A' and 'B', velocity of 'A' relative to ground is given as:

$v_{A,g}=v_{B,g}+v_{A,B}$

Therefore, velocity of Diana relative to ground is given as:

$v_{D,g}=v_{t,g}+v_{D,t}$

$v_{D,g}=(20-4)\ km/h$

$v_{D,g}=16\ km/h$

So, Diana's speed relative to ground is 16 km/h in the direction of motion of train.

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1) The gravitational force between Ellen and the moon is $1.56\cdot 10^{-3} N$

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The magnitude of the gravitational force between two objects is given by

$F=G\frac{m_1 m_2}{r^2}$

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$G=6.67\cdot 10^{-11} m^3 kg^{-1}s^{-2}$ is the gravitational constant

$m_1, m_2$ are the masses of the two objects

r is the separation between them

In this problem, we have:

$m_1 = 47 kg$ is the mass of Ellen

$m_2 = 7.35\cdot 10^{22} kg$ is the mass of the moon

$r=3.84\cdot 10^8 m$ is the distance between Ellen and the moon

Substituting, we find the gravitational force between Ellen and the moon:

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2)

We can analyze the forces acting in the collision between the bus and the bicycle by using Newton's third law of motion, which states that:

"When an object A exerts a force (called action) on an object B, then object B exerts an equal and opposite force (called reaction) on object A"

Applied to our problem, this means that the force exerted by the bus on the bicycle during the collision (action force) is equal (and opposite) to the force exerted by the bicycle on the bus (reaction force).

Now let's analyze the accelerations of the two vehicles. We can find the acceleration of each vehicle by using Newton's second law:

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Learn more about gravitational force:

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