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
IgorC [24]
2 years ago
10

A subway train is traveling at 22.2 m/s when it approaches a slower train 50m ahead traveling in the same direction at 6.94 m/s.

If the faster train begins decelerating at 2.1 m/s 2 while the slower train continues at constant speed, how soon and at what relative speed will they collide?
Physics
1 answer:
Amiraneli [1.4K]2 years ago
4 0

Answer:

Time that they collide = 4.99s

Relative speed of the trains when they collide: The relative speed of The first train relative to the second, slower train at collision = 4.781 m/s

Explanation:

We will use the equations of motion to obtain the solution required

At time t = 0

speed of first train = 22.2 m/s

Initial space between the two trains = 50 m

Speed of second train = 6.94 m/s

For the first car, distance covered by the first train = y

y = distance covered between the beginning of the deceleration and the point where the the two trains hit one another.

u = initial velocity = 22.2 m/s

t = time taken for all this to happen

a = deceleration = - 2.1 m/s²

y = ut + (1/2)at²

y = 22.2t - 1.05t² (eqn 1)

For the second train,

At t = 0, y = 50 m

Let the new distance moved by the second train before collision = (y - 50)

u = initial velocity = 6.94 m/s

t = time taken = t

a = acceleration of the second train = 0 m/s² (constant velocity)

(y - 50) = ut + (1/2)at²

y - 50 = 6.94t

y = 6.94t + 50 (eqn 2)

substituting for y in eqn 2 using the expression obtained in eqn 1

y = 22.2t - 1.05t²

y = 6.94t + 50

22.2t - 1.05t² = 6.94t + 50

1.05t² - 15.26t + 50 = 0

Solving this quadratic equation

t = 4.99 s or 9.54 s

The position of the two trains are the same at those two times, but the first time is when they hit each other.

t = 4.99 s

At 4.99 s, the the velocity of the first train

v = u + at

v = 22.2 + (-2.1×4.99) = 11.721 m/s in the same direction as the second train.

Relative velocity at this point will be

= 11.721 - 6.94 = 4.781 m/s

Relative speed of the trains when they collide: The relative speed of The first train relative to the second, slower train at collision = 4.781 m/s

Hope this Helps!!!

You might be interested in
A rugby player runs with the ball directly toward his opponent's goal, along the positive direction of an x axis. He can legally
Over [174]

Answer:

minimum angle is 128.69°

Explanation:

given data

player velocity with respect ground v1 = 3.5 m/s

ball velocity with respect himself v2 = 5.6 m/s

to find out

smallest angle

solution

we know ball velocity with respect field will be

ball velocity = v1  +v2

ball velocity = 3.5 + 5.6 = 9.1m/s

we consider angle that player hit ball is θ

then by as per figure triangle

cosθ = \frac{v1}{v2}

cosθ = \frac{3.5}{5.6}

θ = 51.31

so minimum angle is 180 - 51.31 = 128.69°

6 0
3 years ago
What is brownion motion
Alex777 [14]

Answer: Brownion motion is the erratic random movement of microscopic particles in a fluid, as a result of continuous bombardment from molecules of the surrounding medium.

Explanation:

Brownian motion is the random movement of particles in a fluid due to their collisions with other atoms or molecules.

4 0
3 years ago
What does a velocity measurement include that a speed measurement does not? A: Time B:direction C:distance D: acceleration​
andrew-mc [135]

Answer:

B. Direction

Explanation:

Speed is a scalar quantity and doesn't keep track of direction : Velocity is a vector quantity and is direction aware.

8 0
2 years ago
What ideas do you have a bout why different places have lower or higher rates of skin cancer?
AnnZ [28]

Answer: Some places like Florida and California are both very hot and dry places, the sun damages your skin more in sunny places then in colder more breezy places.

Explanation:

4 0
2 years ago
The elements from this section of the periodic table all belong to the same
Lady_Fox [76]

Answer:

The answer is:

B) period

3 0
3 years ago
Other questions:
  • What is NOT one of the three primary resources that families have to reach financial goals?
    15·1 answer
  • An electric motor is traversed by 3.10²º electrons in 6 seconds. Determine the intensity of the current passing through the moto
    6·1 answer
  • Based on the information in the graph, which of the atoms listed below is the most stable?
    15·2 answers
  • Calculate the weight of a 25kg object?
    15·1 answer
  • Helium is before lithium on the periodic table because the periodic table arranges elements by increasing ________.
    15·2 answers
  • A box with a mass of 100.0 kg slides down a ramp with a 50 degree angle. What is the weight of the box? N What is the value of t
    12·1 answer
  • Which statements about Earth’s atmosphere are correct? Check all that apply. helpppp
    14·2 answers
  • At what phase or phases could water exist at 4.579mm pressure and 0.0098°C?
    10·1 answer
  • A string is being pulled with a force of 20 N and moves a 5 kg block to the left at a constant speed. What is the coefficient of
    9·1 answer
  • The definition of Force
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!