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Alona [7]
3 years ago
5

A train travelling at 20m/s undergoes a uniform deceleration of 2m/s2 when brakes are applied.. calculate the time taken to come

to rest and distance travel from the place where the brakes were applied ​
Physics
1 answer:
VLD [36.1K]3 years ago
6 0

Answer:

a) 10 seconds

b) 100 meters

Explanation:

<u>Accelerated Motion </u>

If an object is moving at contant speed, we know it has zero net force applied. As soon as an unbalanced force appears, the object accelerates (positive or negative) depending on the direction of the force with respect to movement. The speed of an object subject to acceleration is given by

v_f=v_o+at

The distance traveled is given by

\displaystyle x=v_ot+\frac{at^2}{2}

a)

Our train is travelling at 20m/s when it decelerates at -2\ m/s^2 (negative for it's against movement). If nothing else happens, it will eventually stop (v_f=0). We can compute the time at which it happens :

\displaystyle t=\frac{v_f-v_o}{a}

Knowing\ v_f=0

\displaystyle t=\frac{-20}{-2}=10\ sec

b)

The distance traveled is

\displaystyle x=v_ot+\frac{at^2}{2}

\displaystyle x=(20)(10)-\frac{2(10)^2}{2}

\displaystyle x=100\ m

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Answer:

The time taken is 84 seconds, please give the brainliest award would be much appreciated.

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3 years ago
Water is boiled at sea level in a coffeemaker equipped with an immersion-type electric heating element. The coffee maker contain
Luden [163]

Answer:

P=1362\ W

t'=251.659\ s is time required to heat to boiling point form initial temperature.

Explanation:

Given:

initial temperature of water, T_i=18^{\circ}C

time taken to vapourize half a liter of water, t=18\ min=1080\ s

desity of water, \rho=1\ kg.L^{-1}

So, the givne mass of water, m=1\ kg

enthalpy of vaporization of water, h_{fg}=2256.4\times 10^{-3}\ J.kg^{-1}

specific heat of water, c=4180\ J.kg^{-1}.K^{-1}

Amount of heat required to raise the temperature of given water mass to 100°C:

Q_s=m.c.\Delta T

Q_s=1\times 4180\times (100-18)

Q_s=342760\ J

Now the amount of heat required to vaporize 0.5 kg of water:

Q_v=m'\times h_{fg}

where:

m'=0.5\ kg= mass of water vaporized due to boiling

Q_v=0.5\times 2256.4

Q_v=1.1282\times 10^{6}\ J

Now the power rating of the boiler:

P=\frac{Q_s+Q_v}{t}

P=\frac{342760+1128200}{1080}

P=1362\ W

Now the time required to heat to boiling point form initial temperature:

t'=\frac{Q_s}{P}

t'=\frac{342760}{1362}

t'=251.659\ s

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4 years ago
Find the final velocity
Verizon [17]

Answer: v = 4.4 m/s

Explanation:

In the absence of friction, the total mechanical energy will be constant

KE₀ + PE₀ = KE₁ + PE₁

0 + mg(6) = ½mv₁² + mg(5)

½mv₁² = mg(6 - 5)

v = √(2g(1)) = 4.4 m/s

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3 years ago
HOLA, NECESITO AYUDA!
givi [52]

The electrostatic force between the two ions is 2.9\cdot 10^{-10} N

Explanation:

The electrostatic force between two charged particle is given by Coulomb's law:

F=k\frac{q_1 q_2}{r^2}

where

k=8.99\cdot 10^9 Nm^{-2}C^{-2} is the Coulomb's constant

q_1, q_2 are the two charges

r is the separation between the two charges

In this problem, the ion of sodium has a charge of

q_1 = +e = +1.6\cdot 10^{-19} C

while the ion of chlorine has a charge of

q_2 = -e = -1.6\cdot 10^{-19}C

And the distance between the two ions is

r=282 pm = 282\cdot 10^{-12} m

Substituting, we find the electrostatic force between the two ions:

F=(8.99\cdot 10^9) \frac{(1.6\cdot 10^{-19})(-1.6\cdot 10^{-19})}{(282\cdot 10^{-12})^2}=-2.9\cdot 10^{-10} N

where the negative sign simply means that the force is attractive, since the two ions have opposite charge.

Learn more about electrostatic force:

brainly.com/question/8960054

brainly.com/question/4273177

#LearnwithBrainly

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A car travels along a clear 10.0 km section of motorway in 6.0 minutes. It then drives through 3.0 km of roadwork in 3.0 minutes
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\\ \bull\tt\dashrightarrow Avg\:Speed=\dfrac{Total\:Displacement}{Total\:Time}

\\ \bull\tt\dashrightarrow Avg\:Speed=\dfrac{10+3}{0.1+0.05}

\\ \bull\tt\dashrightarrow Avg\:Speed=\dfrac{13}{0.15}

\\ \bull\tt\dashrightarrow Avg\:Speed=86.6km/h

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2 years ago
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