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jok3333 [9.3K]
3 years ago
6

The velocity of an object with mass = 2kg is given as a function of time:

Physics
1 answer:
Musya8 [376]3 years ago
8 0

Answer:

The force acting on the object at t = 2\,s is \vec F = (4, 32)\,[N].

Explanation:

Given that object has a constant mass in time, the force acting on the object (\vec F), in newtons, is defined by following expression:

\vec F = m\cdot \vec a (1)

Where:

m - Mass, in kilograms.

\vec a - Acceleration, in meters per square second.

By definition of acceleration, we know that:

\vec a = \frac{d}{dt} \vec v (2)

Let suppose that given vector velocity is expressed in meters per second. If we know that m = 2\,kg, \vec v = (2\cdot t, 4\cdot t^{2})\,\left[\frac{m}{s} \right] and t = 2\,s, then the force acting on the object is:

\vec a = (2, 8\cdot t)\,\left[\frac{m}{s^{2}} \right]

\vec F = (4, 16\cdot t)\,[N]

\vec F = (4, 32)\,[N]

The force acting on the object at t = 2\,s is \vec F = (4, 32)\,[N].

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Answer:

When it's closest to the sun.

Explanation:

The force of gravity acting on a planet is equal to its mass times its centripetal acceleration.

Fg = m v^2 / r

The force of gravity is defined by Newton's law of universal gravitation as:

Fg = mMG / r^2

Therefore:

mMG / r^2 = m v^2 / r

MG / r = v^2

v increases as r decreases.  So the planet is moving fastest when it's closest to the sun, also known as the <em>perihelion</em>.

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Answer:

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Explanation:

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Solution A has a specific heat of 2.0 J/g◦C. Solution B has a specific heat of 3.8 J/g◦C. If equal masses of both solutions start
fgiga [73]

Answer: 2. Solution A attains a higher temperature.

Explanation: Specific heat simply means, that amount of heat which is when supplied to a unit mass of a substance will raise its temperature by 1°C.

In the given situation we have equal masses of two solutions A & B, out of which A has lower specific heat which means that a unit mass of solution A requires lesser energy to raise its temperature by 1°C than the solution B.

Since, the masses of both the solutions are same and equal heat is supplied to both, the proportional condition will follow.

<em>We have a formula for such condition,</em>

Q=m.c.\Delta T.....................................(1)

where:

  • \Delta T= temperature difference
  • Q= heat energy
  • m= mass of the body
  • c= specific heat of the body

<u>Proving mathematically:</u>

<em>According to the given conditions</em>

  • we have equal masses of two solutions A & B, i.e. m_A=m_B
  • equal heat is supplied to both the solutions, i.e. Q_A=Q_B
  • specific heat of solution A, c_{A}=2.0 J.g^{-1} .\degree C^{-1}
  • specific heat of solution B, c_{B}=3.8 J.g^{-1} .\degree C^{-1}
  • \Delta T_A & \Delta T_B are the change in temperatures of the respective solutions.

Now, putting the above values

Q_A=Q_B

m_A.c_A. \Delta T_A=m_B.c_B . \Delta T_B\\\\2.0\times \Delta T_A=3.8 \times \Delta T_B\\\\ \Delta T_A=\frac{3.8}{2.0}\times \Delta T_B\\\\\\\frac{\Delta T_{A}}{\Delta T_{B}} = \frac{3.8}{2.0}>1

Which proves that solution A attains a higher temperature than solution B.

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Average velocity =

      (displacement) / (time for the displacement)
and
      (direction of the displacement) .

Displacement =

      (distance from the start-point to the end-point)
and
      (direction from the start-point to the end-point)   .

When Ben is 200 meters from the corner store,
he is (500 - 200) = 300 meters from his house.

His displacement is

         300 meters in the direction
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His average velocity is

         (300/910) =  0.33 meters per second, in the
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