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
motikmotik
3 years ago
13

Baggage on the floor of the baggage car of a high-speed train is not prevented from moving other than by friction. The train is

travelling down a 5 percent grade when it decreases its speed at a constant rate from 144 mi/h to 66 mi/h in a time interval of 12 s. Determine the smallest allowable value of the coefficient of static friction between a trunk and the floor of the baggage car if the trunk is not to slide.
Physics
1 answer:
stich3 [128]3 years ago
8 0

Answer:

 μ = 0.36

Explanation:

This exercise must be solved in parts

Let's start by finding the acceleration of the train, using the kinematics relations

         v = v₀ - a t

         a = \frac{v - v_o}{t}

let's reduce the magnitudes to the SI system

         v = 66 mi / h (5280 ft / 1mile) (1h / 3600s) = 96.8 ft / s

         v₀ = 144 mi / h = 211.2 ft / s

let's calculate

          a = \frac{96.8 - 211.2}{12}

          a = - 9.53 ft / s²

Now we can use Newton's second law, for this let's set a reference system with the x axis parallel to the slope of the hill

let's break down the weight

            sin 5 = Wₓ / W

            cos 5 = W_y / W

            Wₓ = W sin 5

            W_y = W cos 5

Y axis

     N- W_y = 0

     N = W cos 5

   

X axis

      Wₓ -fr = m a

       mg sin 5 - fr = ma

the friction force has the expression

       fr = μ N

       fr = μ W cos 5

we substitute

        mg sin 5 - μ mg cos 5 = ma

        g sin 5 - μ g cos 5 = a

        μ = \frac{g \ sin 5 -a }{g \ cos 5}

        μ =  tan 5 - \frac{a}{ g \ cos 5}

let's calculate

       μ = tan 5 - (-9.53) / 32 cos 5

       μ = 0.08749 + 0.2733

       μ = 0.36

You might be interested in
Classify the waves as longitudinal or transverse.
tresset_1 [31]

Answer:

1. transverse

2. transverse

3. longitudinal

4. idk

Explanation:

8 0
3 years ago
A particle leaves the origin with a speed of 3 106 m/s at 38 degrees to the positive x axis. It moves in a uniform electric fiel
Salsk061 [2.6K]

Answer:

If the particle is an electron E_y = 3.311 * 10^3 N/C

If the particle is a proton, E_y = 6.08 * 10^6 N/C

Explanation:

Initial speed at the origin, u = 3 * 10^6 m/s

\theta = 38^0 to +ve x-axis

The particle crosses the x-axis at , x = 1.5 cm = 0.015 m

The particle can either be an electron or a proton:

Mass of an electron, m_e = 9.1 * 10^{-31} kg

Mass of a proton, m_p = 1.67 * 10^{-27} kg

The electric field intensity along the positive y axis E_y, can be given by the formula:

E_y = \frac{2 m u^2 sin \theta cos \theta}{qx} \\

If the particle is an electron:

E_y = \frac{2 m_e u^2 sin \theta cos \theta}{qx} \\

E_y = \frac{2 * 9.1 * 10^{-31} * (3*10^6)^2 *(sin38)( cos38)}{1.6*10^{-19} * 0.015} \\

E_y = 3311.13 N/C\\E_y = 3.311 * 10^3 N/C

If the particle is a proton:

E_y = \frac{2 m_p u^2 sin \theta cos \theta}{qx} \\

E_y = \frac{2 * 1.67 * 10^{-27} * (3*10^6)^2 *(sin38)( cos38)}{1.6*10^{-19} * 0.015} \\

E_y = 6.08 * 10^6 N/C

8 0
3 years ago
What is the mechanical advantage of the wheel and axle shown below?
goldenfox [79]

Answer:

B. 120

Explanation:

24/.2 = 120

5 0
3 years ago
What are the disadvantages of using alcohol instead of mercury in a thermometer ?​
vichka [17]

Answer:

alcohol thermometers are used rather than Mercury thermometers in very cold regions because alcohol has a lower freezing point than Mercury.

Explanation:

6 0
3 years ago
Consider a situation where you are playing air hockey with a friend. The table shoots small streams of air upward to keep the pu
artcher [175]

When we hit the puck from tap the puck will move forward.

This is due to the impulse provided by us at the time of hit. Due to this impulse the puck will move forward and start moving in some direction.

As soon as puck move forward the force on it is zero as the weight of the puck is counterbalanced by the air stream force and there is no other force on it so puck will continue its motion till it will hit at some other point.

So here the motion of the puck will be uniform motion till it will collide with some other points.

So here the correct option will be given as

<em>moves with a constant speed until hitting the other end.</em>

5 0
3 years ago
Other questions:
  • What is the definition of energy ​
    9·1 answer
  • the amount of surface area of the block contact with the surface is 2.03*10^-2*m2 what is the average pressure exerted on the su
    11·1 answer
  • Cuántas veces es mayor la masa del protón que la del electrón?
    5·1 answer
  • an object that is 8 cm tall is located 2.5 m in front of a plane mirror. The image formed by the mirror appears to be. Find di a
    15·1 answer
  • One-dimensional motion
    9·2 answers
  • Se dea caer una pelota de basquetbol desde una altura de 90 metros.Calcular: El tiempo en que demorara en caer y a velcidad con
    13·1 answer
  • A robin flies a distance of 45963 cm. How far has it flown in kilometers?
    13·1 answer
  • Some thermal containers have layers of materials to keep drinks cold for as long as possible. Which design would help keep ice f
    10·2 answers
  • A water droplet falling in the atmosphere is spherical. Assume that as the droplet passes through a cloud, it acquires mass at a
    5·1 answer
  • hen approaching a curve, it is best to: A. Search for possible collision traps and escape paths B. Stay close to the centerline
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!