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Alla [95]
3 years ago
10

A 2kg mass moving at a speed of 3 m/s is stopped by a constant force of 15N. How many seconds must the force act on the mass to

stop it.
Physics
1 answer:
chubhunter [2.5K]3 years ago
6 0

Answer:

t = 0.4 seconds

Explanation:

Given that,

Mass of the object, m = 2 kg

Initial speed of the object, u = 3 m/s

Finally, it stops, v = 0

Constant force applied to the object, F = 15 N

We know that,

Force, F = ma

F=\dfrac{m(v-u)}{t}\\\\t=\dfrac{m(v-u)}{F}\\\\t=\dfrac{2\times (0-3)}{15}\\\\=0.4\ s

So, it will take 0.4 seconds to stop the mass.

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A coil with an inductance of 2.3 H and a resistance of 14 Ω is suddenly connected to an ideal battery with ε = 100 V. At 0.13 s
klemol [59]

Given Information:

Resistance = R = 14 Ω

Inductance = L = 2.3 H

voltage = V = 100 V

time = t = 0.13 s

Required Information:

(a) energy is being stored in the magnetic field

(b) thermal energy is appearing in the resistance

(c) energy is being delivered by the battery?

Answer:

(a) energy is being stored in the magnetic field ≈ 219 watts

(b) thermal energy is appearing in the resistance ≈ 267 watts

(c) energy is being delivered by the battery ≈ 481 watts

Explanation:

The energy stored in the inductor is given by

U = \frac{1}{2} Li^{2}

The rate at which the energy is being stored in the inductor is given by

\frac{dU}{dt} = Li\frac{di}{dt} \: \: \: \: eq. 1

The current through the RL circuit is given by

i = \frac{V}{R} (1-e^{-\frac{t}{ \tau} })

Where τ is the the time constant and is given by

\tau = \frac{L}{R}\\ \tau = \frac{2.3}{14}\\ \tau = 0.16

i = \frac{110}{14} (1-e^{-\frac{t}{ 0.16} })\\i = 7.86(1-e^{-6.25t})\\\frac{di}{dt} = 49.125e^{-6.25t}

Therefore, eq. 1 becomes

\frac{dU}{dt} = (2.3)(7.86(1-e^{-6.25t}))(49.125e^{-6.25t})

At t = 0.13 seconds

\frac{dU}{dt} = (2.3) (4.37) (21.8)\\\frac{dU}{dt} = 219.11 \: watts

(b) thermal energy is appearing in the resistance

The thermal energy is given by

P = i^{2}R\\P = (7.86(1-e^{-6.25t}))^{2} \cdot 14\\P = (4.37)^{2}\cdot 14\\P = 267.35 \: watts

(c) energy is being delivered by the battery?

The energy delivered by battery is

P = Vi\\P = 110\cdot 4.37\\P = 481 \: watts

4 0
3 years ago
Light striking a metal surface causes electrons to be emitted from the metal via the photoelectric effect.In a particular experi
ANEK [815]

The number of electrons emitted from the metal per second increases if the intensity of the incident light is increased.

Answer: Option B

<u>Explanation:</u>

As a result of photoelectric effect, electrons are emitted by the light incident on a metal surface. The emitted electrons count and its kinetic energy can measure as the function of light intensity and frequency. Like physicists, at the 20th century beginning, it should be expected that the light wave's energy (its intensity) will be transformed into the kinetic energy of emitted electrons.

In addition, the electrons count emitting from metal must vary with light wave frequency. This frequency relationship was expected because the electric field oscillates due to the light wave and the metal electrons react to different frequencies. In other words, the number of electrons emitted was expected to be frequency dependent and their kinetic energy should be dependent on the intensity (constant wavelength) of light.

Thus, the maximum in kinetic energy of electrons emitted increases with increase in light's frequency and is experimentally independent of light intensity. So, the number of emitted electrons is proportionate to the intensity of the incident light.

5 0
3 years ago
In a vertical relationship between an employee and supervisor, who must do most of the adjusting?
maks197457 [2]
Wouldn't it be the employee? Because the employee has to adjust to the needs of his/her supervisor. If the supervisor wants 100 boxes the employee has to make those 100 boxes and so on and so forth.
7 0
3 years ago
When a potassium atom forms an ion, it loses one electron. What is the electrical charge of the potassium ion? *
Ganezh [65]
+1 An electron has a negative charge so losing a charge of -1 from an uncharged, or neutral, atom will leave an ion with a positive charge.
5 0
3 years ago
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The yellow star has much less mass the blue star and so who will live longer
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The yellow star will live longer as it has less mass

8 0
3 years ago
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