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3 years ago

A train traveling at 27.5 m/s accelerates to 42.4 m/s over 75.0 s. What is the displacement of the train in this time period

Physics

1 answer:

Sergio [31]3 years ago

7 0

Answer:

2621.25 meters

Explanation:

First, write down what we are given.

Initial velocity = 27.5 m/s

Final velocity = 42.4 m/s

Time = 75 seconds

We need to look at the kinematic equations and determine which one will be best. In this case, we need an equation with distance. I am going to use $v_{f}^{2} = v_{i}^{2} +2ad$ , but you can also use the other equation, $x = v_{o}t+\frac{1}{2}at^{2}$

We need to find acceleration. To find it, we need to use the formula for acceleration: $a = \frac{v_{f}-v_{i}}{t}$ . Plugging in values, $a = \frac{42.4-27.5}{75} = .199\ m/s^{2}$

Next, plug in what we know into the kinematics equation and solve for distance. $42.4^{2} = 27.5^{2} + 2(.199)(d)\\d = 2621.25\ meters$

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If you have a final velocity of 50 m/s and travelled for 120 seconds. What

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Answer:

a=v-u/t

Explanation:

use this formula and initial velocity is 0

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2 years ago

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Which of the following statements about electromagnetic waves in free space are true? (There could be more than one correct choi

Vanyuwa [196]

Answer:

The electric field carries the same mount of energy as the magnetic field

The frequency of the magnetic field is the same as the frequency of the electric field.

Explanation:

Let's analyze each option in detail:

The electric and magnetic fields have equal amplitudes. --> FALSE. In fact, the amplitudes of the electric and magnetic field are related by the equation:

$E=cB$

where

E is the amplitude of the electric field

B is the amplitude of the magnetic field

c is the speed of light

Therefore, from the equation we see that the amplitude of the electric field is much larger than that of the magnetic field.

The electric field carries the same mount of energy as the magnetic field. --> TRUE.

The energy carried by the electric field is:

$u_E = \frac{1}{2}\epsilon_0 E^2$

where $\epsilon_0$ is the vacuum permittivity.

The energy carried by the magnetic field is:

$u_B = \frac{1}{2\mu_0}B^2$

where $\mu_0$ is the vacuum permeability.

Given the following relationship:

$c=\frac{1}{\sqrt{\epsilon_0 \mu_0}}$

We can write

$E=cB=\frac{1}{\sqrt{\epsilon_0 \mu_0}}B$

$u_E = \frac{1}{2}\epsilon_0 (\frac{1}{\sqrt{\epsilon_0 \mu_0}}B)^2=\frac{1}{2\mu_0}B^2$

which means $u_E=u_B$ .

The electric field carries more energy than the magnetic field. --> FALSE, because in disagreement with the calculations above.

The frequency of the magnetic field is the same as the frequency of the electric field. --> TRUE. In an electromagnetic waves, electric field and magnetic field oscillate at the same frequency.

The frequency of the electric field is higher than the frequency of the magnetic field. --> FALSE, because in disagreement with the previous statement.

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3 years ago

An open container holds ice of mass 0.500 kgkg at a temperature of -17.4 âCâC . The mass of the container can be ignored. Heat i

MaRussiya [10]

Answer:

a) t = 235.2minute

b) 260.94minutes

Explanation:

Heat energy is defined as the energy required to change the temperature of a substance by 1kelvin.

It is expressed as H = mc∆t where m is the mass of the water

c is the specific heat capacity of the water/ice

∆t is the change in temperature

Total heat required to melt the ice

H = mLice + mc∆t

Lice is the latent heat of fusion of ice

a) To calculate how much time tmelts passes before the ice starts to melt, we will only calculate heat energy absorb by the ice before it melts.

H = mLice

H = 0.50(334000)

H = 167,000Joules

If heat is supplied to the container at the constant rate of 710 J/minute, the time taken before the ice starts to melt will be:

t = 167,000/710

t = 235.2minutes

b) To calculate how much time trise does it take before the temperature begins to rise above 0°C, we will calculate the total energy absorbed at 0°C first.

H = 0.50(334000) + 0.50(2100)(0-(-17.4)

Note that the ice melts at 0°C which will be the final temperature

H = 167,000+18270

H = 185,270oules

Since heat is supplied to the container at the constant rate of 710 J/minute

710Joules = 1minute

185,270Joules= x

x = 185,270/710

x = 260.94minutes

The time taken before the temperature begins to rise is 260.94minutes:

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E1 reaction works in the mechanism that the removal of an HX substituent results in the formation of a double bond. The E1 reaction for 2-methylbutan-2-ol is shown in the figure. This reaction is called acid-catalyzed dehydration of a tertiary alcohol.

The mechanism works in three major steps:
1. The OH group of the main reactant is hydrated by H2SO4 so it becomes H2O.
2. The H2O leaves taking electrons with it. This results to a carbocation intermediate on the carbon atom where it was attached.
3. Another H2O protonates the beta carbon. This is the carbon atom next to the carbocation. It will donate its electrons to the neighboring C-C bond, as indicated by the arrow. The carbons are rehybridized from sp3 to sp2, which is a pi bond. As a result, a double bond forms.

The product is 2-methyl-2-butene.