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
rodikova [14]
3 years ago
8

A railroad car of mass 2.52 104 kg is moving with a speed of 3.86 m/s. It collides and couples with three other coupled railroad

cars, each of the same mass as the single car and moving in the same direction with an initial speed of 1.93 m/s. (a) What is the speed of the four cars after the collision? (Round your answer to at least two decimal places.) m/s (b) How much mechanical energy is lost in the collision?
Physics
1 answer:
aleksley [76]3 years ago
6 0

Answer:

a)   v = 2.4125 m / s  , b)  Em_{f} / Em₀ = 0.89

Explanation:

a) This is an inelastic crash problem, the system is made up of the four carriages, so the forces during the crash are internal and the moment is conserved

Initial

          p₀ = m v₁ + 3 m v₂

Final

         p_{f} = (4 m) v

        p₀ =p_{f}

        m (v₁ + 3 v₂) = 4 m v

        v = (v₁ +3 v₂) / 4

Let's calculate

       v = (3.86 + 3 1.93) / 4

       v = 2.4125 m / s

b) the initial mechanical energy is

       Em₀ = K₁ + 3 K₂

       Em₀ = ½ m v₁² + ½ 3m v₂²

       

The final mechanical energy

         Em_{f} = K

         Em_{f} = ½ 4 m v²

The fraction of energy lost is

          Em_{f} / Em₀ = ½ 4m v² / ½ m (v₁² +3 v₂²)

          Em_{f} / Em₀ = 4 v₂ / (v₁² + 3 v₂²)

          Em_{f} / Em₀ = 4 2.4125² / (3.86² + 3 1.93²)

          Em_{f} / em₀ = 23.28 / 26.07

          Em_{f} / Em₀ = 0.89

You might be interested in
Which of the following energy sources is in no way derived from the Sun?
Assoli18 [71]
Tidal, wind, and oil energy are derived from the sun. Nuclear isn't.
7 0
3 years ago
Read 2 more answers
Jerome is learning how the model of the atom has changed over time as new evidence was gathered. He has images of four models of
Stolb23 [73]

Answer:

Y, X, Z, W

Explanation:

You know W is the most recent because it features the nucleus in the middle and the electron cloud which was shown in models after the others.

5 0
3 years ago
Read 2 more answers
HHHEEEEELLLPPPP!!!
SIZIF [17.4K]
The correct answer is the Sun.i hope that helped! if you have any questions or concerns about the answer i gave you please let me know!!
4 0
3 years ago
A softball is thrown from the origin of an X-Y coordinate system with an initial speed of 18 m/s at an angle of 35 degrees above
Goshia [24]
Vo = 18 m/s
angle 35 degrees

1) Components of the initial velocity
 
Vox = Vo*cos(35) = 18*cos(35) m/s = 14.74 m/s
Voy = Vo* sin(35) = 18*sin(35) m/s = 10.32 m/s

2) Equations of postion:

x = Vox*t
y = Voy*t - gt^2 / 2

3) Calculations

A) t = 0.5 s, t = 1.0 st = 1.5 s, t = 2.0 s

x = 14.74 * t

t = 0.5 s => x = 14.74 m/s * 0.5s = 7.37 m

t = 1.0 s => x = 14.74 m/s * 1.0s = 14.74 m

t = 1.5s => x = 22.11 m

t = 2s => x = 29.48 m

B)

y = Voy*t - gt^2 / 2

Voy = 10.32 m/s
g = 10 m/s (approximation)

y = 10.32*t - 5t^2

t = 0.5 s=> y = 3.91m

t = 1 s => y = 5.32m

t = 1.5 s => y = 4.23m

t = 2 s => y = 0.64 m



7 0
3 years ago
The string is fixed at two ends with distance 1.5 m. Its mass is 5 g and the tension in the string is 50N and it vibrates on its
liraira [26]

Answer:

a) \lambda=1\ m

b) f=122.47\ Hz

c) \lambda_s=2.8\ m

Explanation:

Given:

distance between the fixed end of strings, l=1.5\ m

mass of string, m=5\ g=0.005\ kg

tension in the string, F_T=50\ N

a)

<u>Since the wave vibrating in the string is in third harmonic:</u>

Therefore wavelength λ of the string:

l=1.5\lambda

\lambda=\frac{1.5}{1.5}

\lambda=1\ m

b)

We know that the velocity of the wave in this case is given by:

v=\sqrt{\frac{F_T}{\mu} }

where:

\mu= linear mass density

v=\sqrt{\frac{50}{(\frac{m}{l}) } }

v=\sqrt{\frac{50}{(\frac{0.005}{1.5}) } }

v=122.47\ m.s^{-1}

<u>Now, frequency:</u>

f=\frac{v}{\lambda}

f=\frac{122.47}{1}

f=122.47\ Hz

c)

When the vibrations produce the sound of the same frequency:

f_s=122.47\ Hz

Velocity of sound in air:

v_s=343\ m.s^{-1}

<u>Wavelength of the sound waves in air:</u>

\lambda_s=\frac{v_s}{f_s}

\lambda_s=2.8\ m

5 0
3 years ago
Other questions:
  • A 92-kg rugby player running at 7.5 m/s collides in midair with a 112-kg player moving in the opposite direction. After the coll
    7·1 answer
  • According to Newton’s second law of motion, the acceleration of an object equals the net force acting on the object divided by t
    9·1 answer
  • Which type of mirror causes light rays to refract away from each other?
    14·1 answer
  • By what factor should the length of the pendulum of a clock be changed if you want it to run 2 times faster?
    7·2 answers
  • What did the scientist say to the hydrogen atom that claimed it lost an electron
    15·2 answers
  • How could two waves on a rope interfere so the rope does not move at all?
    12·1 answer
  • There is a force between two charges; if the distance between the two charges is doubled, by what factor does the force between
    9·2 answers
  • Which point or points on the image below show constructive interference of light? *
    12·2 answers
  • You walk 12.0 m West and then 4.00 m south. What is your displacement?​
    11·1 answer
  • Plz help I will mark as brainlest plz help me
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!