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aleksandr82 [10.1K]
3 years ago
10

A train traveled 100 kilometers north in 2 hours. After exchanging some railroad cars, it traveled 100 kilometers south in 2 hou

rs along the same track. Why has the train's velocity changed
Physics
1 answer:
hodyreva [135]3 years ago
7 0

Answer:Due to change in direction

Explanation:

Given

Initially train has traveled a 100 km in North and after exchanging some railroad cars, it traveled 100 in south.

The velocity of the train changes as it direction of motion changes. Velocity is the vector quantity which require direction and magnitude for its reperesentation.

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Sum of the individual forces
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3 years ago
PLEASE HELP. A substance decays according the the equation ae^-0.0025t, where t is in minutes. Find the half life of the substan
mojhsa [17]

First of all, that's not an equation.  An equation needs an 'equals' sign ( = ),
so you need something like 

               Amount present = a e^-0.0025t .

                                   'a' = amount present when t = 0 .

The half-life is the time it takes for the original amount to decay to half of it.

That's just 't' when                      e^-0.0025t  =  1/2

Take the natural log of each side:    -0.0025t  =  ln(0.5)

Divide each side by  -0.0025 :        t = ln(0.5) / (-0.0025) =

                                                     (-0.69315) / (-0.0025) =

                                                   <em>t  =  277.26 minutes</em>

                                                    ( 4hrs 37min 15.5sec)

Rounded to nearest tenth:  t = 277.3 minutes .


3 0
4 years ago
I don’t get this question please help me
zvonat [6]

oof, that question is difficult! i would say its d because if you pull a slingshot farther than another one, it would have more potential energy.

6 0
3 years ago
Read 2 more answers
What is the distance from axis about which a uniform, balsa-wood sphere will have the same moment of inertia as does a thin-wall
andrey2020 [161]

Answer:

D_{s} ≈ 2.1 R

Explanation:

The moment of inertia of the bodies can be calculated by the equation

     I = ∫ r² dm

For bodies with symmetry this tabulated, the moment of inertia of the center of mass

Sphere               Is_{cm} = 2/5 M R²

Spherical shell   Ic_{cm} = 2/3 M R²

The parallel axes theorem allows us to calculate the moment of inertia with respect to different axes, without knowing the moment of inertia of the center of mass

    I = I_{cm} + M D²

Where M is the mass of the body and D is the distance from the center of mass to the axis of rotation

Let's start with the spherical shell, axis is along a diameter

     D = 2R

    Ic = Ic_{cm} + M D²

    Ic = 2/3 MR² + M (2R)²

    Ic = M R² (2/3 + 4)

    Ic = 14/3 M R²

The sphere

    Is =Is_{cm} + M [D_{s}²

    Is = Ic

    2/5 MR² + M D_{s}² = 14/3 MR²

    D_{s}² = R² (14/3 - 2/5)

    D_{s} = √ (R² (64/15)

    D_{s} = 2,066 R

3 0
3 years ago
A 0.200-kg mass is attached to the end of a spring with a spring constant of 11 N/m. The mass is first examined (t = 0) when the
inn [45]

Answer:

a) x (t) = 0.3187 cos (7.416 t + 1.008) ,  b)  v = -2,363 sin (7,416 t + 1,008)

c)  a = - 17.52 cos (7.416t + 1.008)

Explanation:

The spring mass system creates a harmonic oscillator that is described by the equation

    x = Acos (wt + φ)

Where is the amplitude, w the angular velocity and fi the phase

a) Let's reduce the SI system

    x = 17.0 cm (1 m / 100 cm) = 0.170 m

The angular velocity is given by

      w = √ (k / m)

      w = √ 11 / 0.200

      w = 7.416 rad / s

Let's look for the terms of the equation with the data for time zero (t = 0 s)

      0.170 = A cos  φ

Body speed can be obtained by derivatives

      v = dx / dt

      v = -A w sin (wt + φ)

     2.0 = -A 7.416 sin φ

Let's write the two equations

     0.170 = A cos φ

     2.0 / 7.416 = -A sin φ

Let's divide those equations

    tan φ= 2.0 / (7.416 0.170)

     φ= tan⁻¹ (1,586)

     φ= 1.008 rad

We calculate A

   A = 0.170 / cos φ

   A = 0.170 / cos 1.008

   A = 0.3187 m

With these values ​​we write the equation of motion

    x (t) = 0.3187 cos (7.416 t + 1.008)

b) the speed can be found by derivatives

      v = dx / dt

      v = - 0.3187 7.416 sin (7.416 t +1.008)

      v = -2,363 sin (7,416 t + 1,008)

c) the acceleration we look for conserved

    a = dv / dt

    a = -2,363 7,416 cos (7,416 t + 1,008)

    a = - 17.52 cos (7.416t + 1.008)

6 0
3 years ago
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