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spayn [35]
2 years ago
15

A student is gliding along on a scooter at a comfortable 2.8 m/s when Mr. Jones walks around the corner and the two collide. If

the student is brought to rest in 0.15 s, what is their acceleration (hint: should it be acceleration or deceleration)?
Physics
1 answer:
faltersainse [42]2 years ago
6 0

Answer:

Their deceleration is - 19 \frac{m}{s^{2} }

Explanation:

Acceleration is a quantity that indicates how the speed of the object changes over time. In other words, acceleration is a vector quantity that relates changes in velocity to the time it takes to occur. It is normally represented by the letter a and its unit of measurement, in the International System it is meters per second squared \frac{m}{s^{2} }.

The mathematical expression for the acceleration is:

a=\frac{final speed - initial speed}{final instant - initial instant}

In this case:

  • final speed= 0 \frac{m}{s}
  • initial speed= 2.8 \frac{m}{s}
  • final instant=0.15 s
  • initial instant= 0 s

Replacing:

a=\frac{0 \frac{m}{s} - 2.8\frac{m}{s} }{0.15 s - 0s}

a= -18. 667 \frac{m}{s^{2} } ≅ -19 \frac{m}{s^{2} }

Deceleration is a quantity that expresses the passage of a moving body from one speed to a lower speed. Mathematically it is calculated as the acceleration but the result will be a negative acceleration.

<u><em>Their deceleration is - 19 </em></u>\frac{m}{s^{2} }<u><em></em></u>

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kondaur [170]

Answer:

endothermic reactions

8 0
3 years ago
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Assume that the position vector of A is r=i+j+k . Determine the moment about the origin O if the force F=(1)i+(0)j+(5)k . The mo
ddd [48]

Answer:

M₀ = 5i - 4j - k

Explanation:

Using the cross product method, the moment vector(M₀) of a force (F) is about a given point is equal to cross product of the vector A from the point (r) to anywhere on the line of action of the force itself. i.e

M₀ = r x F

From the question,

r = i + j + k

F = 1i + 0j +  5k

Therefore,

M₀ = (i + j + k) x (1i + 0j +  5k)

M₀ = \left[\begin{array}{ccc}i&j&k\\1&1&1\\1&0&5\end{array}\right]

M₀ = i(5 - 0) -j(5 - 1) + k(0 - 1)

M₀ = i(5) - j(4) + k(-1)

M₀ = 5i - 4j - k

Therefore, the moment about the origin O of the force F is

M₀ = 5i - 4j - k

3 0
2 years ago
1. Which statement about subatomic particles is not true?
igomit [66]

1. Protons and neutrons have the same charge.

Protons have positive charge, equal to e=+1.6\cdot 10^{-19} C, while neutrons have zero charge.

2. mass number

The mass number of an atom is equal to the sum of protons and neutrons inside its nucleus.

3. Atoms are made up of smaller particles.

According to Dalton's theory, atoms are the smallest particles that make matter, and they are indivisible and indestructible, so they are NOT made up of smaller particles.

4. a solid sphere

In Dalton's theory, atoms are not made of smaller particles, so we can think them as solid spheres.

5. J. J. Thomson

In his experiment with cathode ray tubes, JJ Thomson demonstrated the existance of the electrons, which are negatively charged particles inside the atom. In his model of the atom (plum-pudding model), Thomson thought the atom consists of a uniform positive charge and the electrons are located inside this positive charge.

6. An electron has the same amount of energy in all orbitals.

In fact, each orbital corresponds to a different energy level: the farther the orbital from the nucleus, the higher the energy of the electrons contained in that orbital.

7. A hydrogen atom in heavy water has an extra neutron.

Heavy water is a type of water that contains deuterium, which is an isotope of the hydrogen consisting of one proton and one neutron (so, one extra neutron).

8. The glowing beam was always deflected by charged plates

In his cathode's ray tube experiment, Thomson shows that the beam of unknown particles (= the electrons) were deflected by charge plates, so the particles had to be also electrically charged.

9. electrons move to a lower energy level

When electrons move from a higher energy level to a lower energy, they emit a photon (light) of energy equal to the difference in energy between the two energy levels.

10. orbital

In quantum mechanics, electrons in the atom are not precisely located, since we cannot determine their exact position and velocity at the same time. Therefore, we can only describe regions of space where the electrons have a certain probability to be found, and these regions of space are called orbitals.

11. 14

According to Dalton's theory, the proportions of the reactants must be respected in order to form the same compound. Therefore, we can write:

2 g: 4 g = X : 28 g\\X=\frac{2 g \cdot 28 g}{4 g}=14 g

12. negative charge, found outside the nucleus

Electrons are particles with negative charge of magnitude e=-1.6\cdot 10^{-19}C that orbit around the nucleus. The nucleus, instead, consists of protons (positively charged, with charge opposite to the electron) and neutrons (neutrally charged).

13. move from higher to lower energy levels

When electrons move from a higher energy level to a lower energy inside a neon atom, they emit a photon (which is light) whose energy is equal to the difference in energy between the two energy levels.

14. atomic number from its mass number

In fact:

- the atomic number of an atom (Z) is equal to the number of protons inside the nucleus

- the mass number of an atom (A) is equal to the sum of protons+neutrons inside the nucleus

Therefore, we can find the number of neutrons in the nucleus by calculating the difference between A and Z:

Number of neutrons = A - Z

15. None of them

None of these examples is a good analogy to describe the location of an electron in an atomic orbital: in fact, the position of an electron in an orbital cannot be precisely described, we can only describe the probability to find the electron in a certain position, and none of these example is an analogy of this model.

8 0
3 years ago
En que parte de la isla de cuba tuvieron lugar los principales acontecimientos de la guerra de independencia?
DedPeter [7]

Answer:

El 24 de febrero de 1895, por órdenes de Martí se levantan 35 aldeas en el Oriente de Cuba en lo que se ha dado en llamar el Grito de Baire.

Entre los lugares están Ibarra, Guantánamo y Manzanillo.

Explanation:

8 0
3 years ago
A train car with mass m1 = 515 kg is moving to the right with a speed of v1 = 7.5 m/s and collides with a second train car. The
Anna [14]

Answer:

For the first situation, we first need to find the mass of the second train car.

In order to do that, we apply the conservation of the amount of movement:

515*7.5+m2*0=(m1+m2)*4.8

and we have as a result:

m2 = 289.6875

For the second situation, also we will apply the conservation of the amount of movement:

515*7.5-289.6875*6 = (515+289.6875)*V

and we have as a result:

V = 2.64 (it is moving to the right)

6 0
3 years ago
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