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
Zolol [24]
3 years ago
13

An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the ten

sion in the cable and the gravity. Which one of the following statements is correct? Group of answer choices
A. The work done by the gravity is zero joules.
B. The tension force does positive work.
C. The net work done by the two forces is zero joules.
D. The work done by the tension force is zero joules.
E. The gravitational force does negative work.
Physics
1 answer:
VikaD [51]3 years ago
3 0

Answer:

C. The net work done by the two forces is zero joules.

Explanation:

Work (W) is defined as the product of force F) by the distance (d)the body travels due to this force.  

W= F*d Formula ( 1)

The work is positive (W+) if the force has the same direction of movement of the object.  

The work is negative (W-) if the force has the opposite direction of the movement of the object.

The component of the force that performs work must be parallel to the displacement.  

Calculation of the forces

We apply Newton's second law:

∑F = m*a

∑F : algebraic sum of the forces in Newton (N)

m : mass in kilograms (kg)

a : acceleration in meters over second square (m/s²)

∑F = m*a  

a = 0 because the elevator moves at constant speed.

∑F=0

T-W = 0

T = W  

Calculation of work done by the forces

W₁ :  work done by the gravity= (+ W*d ) J

W₂ : work done by the tension force=( -T*d) J

Net work done by the two forces(W₁-W₂):

W₁= W₂ .because T = W  

W₁-W₂ =0

You might be interested in
Your heart pumps blood at a pressure of 100 mmHg and flow speed of 60 cm/s. At your brain, the blood enters capillaries with suc
Savatey [412]

Answer:

1.28 m

Explanation:

Generally, pressure of fluid is given by

P=\rho g h where g is acceleration due to gravity, h is the height and \rho is the density

Considering that the pressure for mercury is same as for blood only that the height and density of fluid are different then

\rho_b g h_b= \rho_m g h_m

Since g is constant, then

\rho_b h_b= \rho_m h_m

Making h_b the subject of the formula then

h_b=\frac {\rho_m h_m}{\rho_b}

Where subscripts m and b denote mercury and blood respectively

Assuming density of blood is 1060 Kg/m3, density of mercury as 13600 Kg/m3 and substituting height of mercury for 0.1 m then

h_b=\frac {13600*0.1}{1060}=1.283018868  m \approx 1.28 m

7 0
3 years ago
What happens when an electron absorbs energy?
Klio2033 [76]

Answer:

C

Explanation:

Its because electron does its thing with energy to

its orbital

4 0
3 years ago
How can we avoid injuries in school or community when engaging in physical activities?
Mazyrski [523]

Answer:

  • we should not fight with each other
3 0
3 years ago
Determine the energy required to accelerate an electron between each of the following speeds. (a) 0.500c to 0.900c MeV (b) 0.900
Aleonysh [2.5K]

Answer:

The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.

Explanation:

We know that,

Mass of electron m_{e}=9.11\times10^{-31}\ kg

Rest mass energy for electron = 0.511 Mev

(a). The energy required to accelerate an electron from 0.500c to 0.900c Mev

Using formula of rest,

E=\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{f}^2}{c^2}}}-\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{i}^2}{c^2}}}

E=\dfrac{0.511}{\sqrt{1-\dfrac{(0.900c)^2}{c^2}}}-\dfrac{0.511}{\sqrt{1-\dfrac{(0.500c)^2}{c^2}}}

E=0.582\ Mev

(b). The energy required to accelerate an electron from 0.900c to 0.942c Mev

Using formula of rest,

E=\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{f}^2}{c^2}}}-\dfrac{E_{0}}{\sqrt{1-\dfrac{v_{i}^2}{c^2}}}

E=\dfrac{0.511}{\sqrt{1-\dfrac{(0.942c)^2}{c^2}}}-\dfrac{0.511}{\sqrt{1-\dfrac{(0.900c)^2}{c^2}}}

E=0.350\ Mev

Hence, The energy required to accelerate an electron is 0.582 Mev and 0.350 Mev.

4 0
3 years ago
How long does it take an automobile traveling 66.7 km/h to become even with a car that is traveling in another lane at 52.7 km/h
tresset_1 [31]

Answer:

The  time taken is  t =  32.5 \  s

Explanation:

From the question we are told that

   The  speed  of  first car is  v_1  =  66.7 \ km/h  =  18.3 \  m/s

    The  speed  of  second car is v_2  =  52.7 \ km/h  =  14.64 \  m/s

   The  initial distance of separation is  d =  119 \ m

The distance covered by first car is mathematically represented as

     d_t =  d_i  +  d_f

Here  d_i is the initial distance which is  0 m/s

  and  d_f  is the final distance covered which is  evaluated as d_f  =  v_1 * t

So

     d_t =  0 \  m/s  +  (v_1 * t )

     d_t =  0 \  m/s  +  (18.3 * t )

The distance covered by second  car is mathematically represented as

     d_t =  d_i  +  d_f

Here  d_i is the initial distance which is  119 m

  and  d_f  is the final distance covered which is  evaluated as d_f  =  v_2* t

       d_t =  119  + 14.64 *  t

Given that the two car are now in the same position we have that

    119  + 14.64 *  t  =   0   +  (18.3 * t )

   t =  32.5 \  s

6 0
3 years ago
Other questions:
  • What layer is just below the Earth’s crust?
    8·1 answer
  • Use complete sentences to describe an extra-solar (exo) planet
    12·2 answers
  • What is unit of pressure
    13·2 answers
  • How do magnetics ruin electronic devices
    5·2 answers
  • A 12,500 kg railroad freight car travels on a level track at a speed of 5.2 m/s. It collides and couples with a 22,600 kg second
    8·1 answer
  • Se coloca una tuerca con una llave, como muestra la figura, si el brazo r= 30 cm y el torque de apriete recomendado para la fuer
    13·1 answer
  • Tammy leaves the office, drives 26 km due
    11·1 answer
  • How do mass and distance affect the gravitational force between two objects?
    8·1 answer
  • I HAVE NOOOO IDEA!!!!!!!!!! HELP!!!!!!!!!!
    6·1 answer
  • If the distance between two charged particles is increased 2.69 times, the ratio of new to old electric force is _______ times t
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!