1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
LekaFEV [45]
3 years ago
12

A train 400 m long is moving on a straight track with a speed of 81.4 km/h. The engineer applies the brakes at a crossing, and l

ater the last car passes the crossing with a speed of 17.6 km/h. Assuming constant acceleration, determine how long the train blocked the crossing. Disregard the width of the crossing.
Physics
1 answer:
Luda [366]3 years ago
3 0

Answer:

86.5m

Explanation:

first convert km/h

then

81.4*1000/60*60=22.6

17.6*1000/60*60=4.89

then, x1/t1=x2/t2

we get

x2=400*4.89/22.6=86.5//

You might be interested in
one group of atoms on the periodic tables are known as "noble gases". why have they been given this name?​
maria [59]
This group is called “noble gases” because they do not react with other elements. This is because they have a full valence shell.
8 0
3 years ago
The Atomic number tells us the number of ____ in an atom.
yawa3891 [41]

Answer:

Protons

Explanation:

5 0
3 years ago
Read 2 more answers
Potassium is a crucial element for the healthy operation of the human
Degger [83]

Answer:

1

  The mass of the Potassium-40 is  m_{40}} = 2.88*10^{-6} kg

2

  The Dose per year in Sieverts is   Dose_s = 26.4 *10^{-10}

Explanation:

From the question we are told that

   The isotopes of potassium in the body are Potassium-39, Potassium-40, and Potassium- 41

    Their abundance is 93.26%, 0.012% and 6.728%

   The mass of potassium contained in human body is  m = 3.0 g = \frac{3}{1000} = 0.0003 \ kg per kg of the body

    The mass of the first body is  m_1 = 80 \ kg

Now the mass of  potassium  in this body is mathematically evaluated as

       m_p =  m * m_1

substituting value

       m_p =  80  * 0.0003

      m_p  =0.024 kg

The amount of Potassium-40 present  is mathematically evaluated as

      m_{40}} =0.012% * 0.024

      m_{40}} = \frac{0.012}{100}  * 0.024

      m_{40}} = 2.88*10^{-6} kg

The dose of energy absorbed per year is mathematically represented as

          Dose  = \frac{E}{m_1}

Where E is the energy absorbed which is given as E = 1.10 MeV = 1.10 * 10^6 * 1.602*10^{-19}

    Substituting value

            Dose  = \frac{ 1.10 * 10^6 * 1.602*10^{-19}}{80}

            Dose  = 22*10^{-10} J/kg

The Dose in Sieverts is evaluated as

       Dose_s = REB * Dose

       Dose_s = 1.2 * 22*10^{-10}

       Dose_s = 26.4 *10^{-10}

             

3 0
3 years ago
Which type of energy is stored in chemical compounds and released in chemical reactions?
astraxan [27]

Answer:

potential

Explanation:

4 0
3 years ago
An elevator starts from rest with a constant upward acceleration and moves 1 m in the first 1.7 s. A passenger in the elevator i
avanturin [10]

Answer: Tension = 53.6N

Explanation:

Given that

Height h = 1 m

Time t = 1.7 s.

Mass m = 5.1 kg 

From the equation of the motion we can get the acceleration of the elevator:

h = X0+ V0t + at2/2;

Th elevator starts from rest with a constant upward acceleration. Initial velocity Vo = 0, also Xo = 0; thus

a = 2h/t2 = 2 × 1/1.7^2

a = 0.69 m/s2.

Then we can find the tension in the cord by using the formula

T = mg + ma

= 5.1 (9.8 + 0.69)

= 5.1 × 10.5

= 53.6N

7 0
3 years ago
Other questions:
  • A baseball is thrown vertically up to a height of 30 m on Earth. If the same ball is thrown up on the moon with the same initial
    6·1 answer
  • What does a lunar eclipse and a solar eclipse have in common
    5·1 answer
  • A plane travels 1000 miles in 5 hours .what is the planes average speed?
    13·2 answers
  • If many household substances classify as acids or bases what is the ph scale
    15·1 answer
  • Would you rather be beautiful but you cant look at yourself or be ugly and no one else can see you
    12·1 answer
  • Through which media did sound waves travel the fastest and the slowest?
    8·1 answer
  • A bowling ball with a mass of 8 kg is moving at a speed of 5 m/s. What is its<br> kinetic energy?
    9·1 answer
  • A 1kg dictionary is resting on a table that is 1.5m high. How much potential energy
    14·1 answer
  • Which of the following statement describes a nonpolar molecule
    6·2 answers
  • Metals are used in many products because of the characteristic properties that most metals have.
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!