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Phantasy [73]
3 years ago
7

An elevator and counterweight are like Atwood’s machine. An elevator, M=100kg, has a counter weight m=90kg connected by a cable

over a massless pulley with no friction. The elevator falls, starting from rest, a distance 20.5 m and lands. What the final kinetic energy of the system, in J, just before the elevator lands?
Physics
1 answer:
crimeas [40]3 years ago
6 0

Answer:

v = 6.34 m / s

Explanation:

For this exercise let's use the concept of mechanical energy, write the energy of the system (elevator plus counterweight) at two points

Initial. Elevator highest point

The elevator mass is M and that of the counterweight m

     Em₀ = U = M g h + mg (0)

The counterweight is on the floor

Final. elevated at the lowest point

    Em_{f} = K + U = ½ M v² + Mg (0) + m g h

as there is no friction

    Em_{f} = Em₀

   ½ M v² + m g h = M g h

   v² = (M-m) gh 2 / M

  v = √ [(100-90) 9.8 20.5 2/100]

  v = √ 40.18

  v = 6.34 m / s

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a)   a = - 0.0833 m / s²,  b)   t = 4.4 s

Explanation:

a) this is a kinematics exercise where the acceleration is along the inclined plane

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         a = 3 - 8/60

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b) in this case the final velocity is zero

         v = v₀ - a t

         0 = v₀ - at

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         t = 28 / 6.4

         t = 4.375 s

         t = 4.4 s

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At 13:20 on the last Friday in September, 1989 a frantic call was received at the local police station. There had been a serious
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The kinematics and conservation of momentum relationships allow to find the results for the questions about the measurements and conditions to know the accident conditions are:

     1) The principles of conservation of momentum  and kinematics.

     2)  \theta = tan^{-1} \frac{P_{01}}{p_{02}}

     3) The factors that influence the direction and distance traveled are:

         The initial speed of the vehicles

         The mass of the vehicles

         Pavement conditions: dry, wet, humid, with dirt or loose sand.

1) Kinematics studies the movement of bodies, they look for relationships between position, speed and acceleration.

To analyze the accident, you must answer a question such as what speed the vehicles had before the accident, this is the initial speed of each one and their directions.

When reviewing the kinematics relationships we have.

        v^2 = v_o^2 - 2 a x  

Where the acceleration is given by Newton's second law.

        fr = m a

The friction force is given by the expression.

       fr = μ N  

       fr = μ mg

       

Let's Substitute.

         μ m g = m a

         a = μ g

The friction coefficient is tabulated, for different types of rubber, pavement and wet,  dry conditions, etc.

Therefore, the researcher must measure the braking distance of the vehicles, which can be taken from the mark of the tires on the road and note the condition of the pavement if it is dry or wet and the visibility of the day.

This is the speed of the vehicles just after the impact, using the law of conservation of momentum you can find the speed of the vehicles before the impact

        p_o = p_f \f

         

Where this is a vector expression, which in general is solved with the components of each directional.

Consequently to answer the questions you must use the principles of conservation of momentum  and kinematics.

2) If the vehicles travel at right angles and their masses are similar, the direction after the collision  in each direction.

           tan \theta = \frac{p_{01}}{p_{02}}  

           \theta = tan ^{-1} \frac{p_{01}}{p_{02}}  

3) The factors that influence the direction and distance traveled are:

     The initial speed of the vehicles

     The mass of the vehicles

     Pavement conditions: dry, wet, humid, with dirt or loose sand.

In conclusion, using the kinematics and conservation of momentum relationships, we can find the answers to the question about measurements and conditions to know the accident conditions are:

      1) The principles of conservation of momentum  and kinematics.

     2)  \theta = tan^{-1} \frac{P_{01}}{p_{02}}

     3) The factors that influence the direction and distance traveled are:

         The initial speed of the vehicles

         The mass of the vehicles

         Pavement conditions: dry, wet, humid, with dirt or loose sand.

Learn more about kinematics and momentum here:   brainly.com/question/17304001

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