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3 years ago

A train departs from its station at a constant acceleration of 5 m/s. What is the speed of the train at the end of 20s?

Physics

2 answers:

shutvik [7]3 years ago

7 0

Answer:

Velocity, v = 100 m/s

Explanation:

It is given that,

Initial speed of the train, u = 0

Acceleration of the train, $a=5\ m/s^2$

Let v is the velocity of the train at the end of 20 seconds, t = 20 s

Using the equation of kinematics as :

v = u + a × t

v = a × t

v = 5 × 20

v = 100 m/s

So, the velocity of the train after 20 s is 100 meters. Hence, this is the required solution.

morpeh [17]3 years ago

4 0

Acceleration = (final velocity-initial velocity)/time
5 = (v-0)/20
v = 100m/s

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A rocket carrying a satellite is accelerating straight up from the earth’s surface. At 1.15 s after liftoff, the rocket clears t

yarga [219]

Answer:

197.263157895 m/s

169.491525424 m/s

Explanation:

x Denotes position

t Denotes time

Average velocity is given by

$v_a=\dfrac{x_2-x_1}{t_2}\\\Rightarrow v_a=\dfrac{1000-63}{4.75}\\\Rightarrow v_a=197.263157895\ m/s$

The average velocity is 197.263157895 m/s

$v_a=\dfrac{x_2-x_1}{t_2}\\\Rightarrow v_a=\dfrac{1000-0}{5.9}\\\Rightarrow v_a=169.491525424\ m/s$

The average velocity is 169.491525424 m/s

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3 years ago

A 40.0-mH inductor is connected to a North American electrical outlet (ΔVrms = 120 V, f = 60.0 Hz). Assuming the energy stored i

trasher [3.6K]

Explanation:

It is given that,

Inductance, $L=40\ mH=40\times 10^{-3}\ H$

RMS value of voltage, $v_{rms}=120\ V$

Frequency, f = 60 Hz

We need to find the energy stored at t = (1 /185) s. It is assumed that energy stored in the inductor is zero at t = 0. So,

The current flowing through the inductor is given by :

$I_t=\dfrac{V_o}{X_L}\ (sin\ \omega t-\dfrac{\pi}{2})$

$I_t=\dfrac{\sqrt{2} V_{rms}}{X_L}\ (sin\ \omega t-\dfrac{\pi}{2})$

$I_t=\dfrac{120\sqrt{2}}{2\pi f L}\ sin(2\pi f t-\dfrac{\pi}{2})$

$I_t=\dfrac{120\sqrt{2}}{2\pi\times 60\times 40\times 10^{-3}}\ sin(2\pi \times 60\times \dfrac{1}{185})-\dfrac{\pi}{2})$

$I_t=\dfrac{120\sqrt2}{15.07}\ sin(2\pi \times 60\times \dfrac{1}{185}-\dfrac{\pi}{2})$

I = 0.091 A

Energy stored in the inductor is, $U=\dfrac{1}{2}LI^2$

$U=\dfrac{1}{2}\times 40\times 10^{-3}\times (0.091)^2$

U = 0.000165 Joules

Hence, this is the required solution.

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3 years ago

A brick falls from a wall to the ground 3.42 m below. How much time will it take to

ddd [48]

Answer:

The time taken by the brick to hit the ground, t = 0.84 s

Explanation:

Given that,

A brick falls from a height, h = 3.42 m

The initial velocity of the brick is zero.

Since the brick is under free-falling. The time equation of a free-falling body when the displacement is given is

t = $\sqrt{2h/g}$

where,

h - height from surface in meters

g - acceleration due to gravity

on substituting the values in the above equation,

t = $\sqrt{2X3.14/9.8}$

= 0.84 s

Hence, time taken by the brick to hit the ground is t = 0.84 s

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3 years ago

b. A string is wrapped around a pulley of radius 0.05 m and moment of inertia 0.2 kg  m2. If the string is pulled with a force

Oduvanchick [21]

Answer:

f = 8 N

Explanation:

Data provided in the question

Radius of the pulley = r = 0.05 m

Moment of inertia = (I) = 0.2 kg.m^{2}

Angular acceleration = ∝ = 2 rad/sec

Based on the above information

As we know that

Torque is

$= force \times radius$

$= f \times r$

And,

Torque is also

$= moment\ of\ inertia \times angular\ acceleration$

$= I \times \alpha$

So,

We can say that

$f \times r = I \times \alpha$

$f \times 0.05 = 0.2 \times 2$

0.05f = 0.4

f = 8 N

We simply applied the above formulas

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3 years ago

A rocket is fired from rest from the ground (y = 0) at time t0 = 0 s. As the rocket is burning its fuel, it moves vertically upw

elixir [45]

Answer:

Explanation:

attached is the solution

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3 years ago