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
Katen [24]
3 years ago
8

One block rests upon a horizontal surface. A second identical block rests upon the first one. The coefficient of static friction

between the blocks is the same as the coefficient of static friction between the lower block and the horizontal surface. A horizontal force is applied to the upper block, and its magnitude is slowly increased. When the force reaches 41.6 N, the upper block just begins to slide. The force is then removed from the upper block, and the blocks are returned to their original configuration. What is the magnitude of the horizontal force that should be applied to the lower block, so that it just begins to slide out from under the upper block?

Physics
1 answer:
goblinko [34]3 years ago
4 0

Answer:

The magnitud of the force is 124.8N.

Explanation:

First we have to find the value of the static friction coefficient, when the external force F is applied to upper block (i will call it A Block) we have a free body diagram as the one shown in the figure i attached, so since this block has no aceleration in any direction the force F should be equal to the friction force between A and B block, one we noticed this we can use the equation for the Friction force to find the coefficient:

0=F-FrictionAB

F=FrictionAB=Nab*μs

and again, since the block has no acceleration the normal between A and B block should be equal to the weigth of the first block, so we have:

0=Nab-W

Nab=W=mg

replacing this we have:

F=μs*Nab=μs*mg=41.6N

and  μs=41.6N/(mg)

now it's time to see the free body diagram for the b block, if we now apply the F force to the B block the diagram should look like in the figure.

the color of the arrow gives you an idea of where the force comes from, the blue ones comes from the B block, the red ones from the A block and the brown ones from the ground.

now for the B block you can see two friction forces, one for the ground and one for the A block, both of these directed bacwards, and two normal forces, again one for the ground and one for the A block but the normal force for the A block is aiming downwards.

again we use the fact that the block is not accelerating in any direction so the sum of the forces in x and y direction have to be 0, so:

F-Friction1(ground)-Friction2(AB)=0

This is the new external F force that we are looking for:

F=Friction1(ground)+Friction2(AB)

we know Friction2(AB) because we found that in the previous block so:

F=Friction1(ground)+mg*μs

for the other friction we have to use the equation:

Friction(ground)=N(ground)*μs

from y axis we have:

N(ground)-w-Normal(AB)=0

N(ground)=w+Normal(AB)

we found the value of Normal(AB) with the previous block so:

N(ground)=mg+mg=2mg

and:

Friction(ground)=2mg*μs

F=Friction(ground)+mg*μs

F=2mg*μs+μs*mg=3mg*μs

and since: μs*mg=41.6N

the new F force would be:

F=3mg*μs=41.6*3=124.8N

You might be interested in
A bird accelerating from rest at a constant rate,experiences a displacement of 28 m in 11s.What is its acceleration
Ksenya-84 [330]
Use the formula below for this question:

v_{f} = v_{i} + 2 * a * d

re-arrange to solve for a:

a = \frac{v_{f} - v_{i}}{2 * d}

now simply plug in your variables and there's your answer :). If you ever get stuck, you can look up the kinematic equations!
4 0
3 years ago
How is heat converted into work in a steam engine?
Dmitry_Shevchenko [17]
In an extremely simplified explanation,
What happens is that the steam (heat) that is generated by the burning of coal is used to rotate the motor of the steam engine.
8 0
3 years ago
1. A car is slowing down at a constant rate from 40 m/s to come to a stop. The acceleration is - 5 m/s2. How
Oxana [17]

Answer:

           

Explanation:

5 0
2 years ago
A skier (down a straight course) is able to enter the starting gate with a speed of 1 m/sec and the average acceleration down th
Zigmanuir [339]
He was moving at 31 m/s
3 0
3 years ago
Motor oil , with a viscosity of 0 . 250 Ns / m2 , is flowing through a tube that has a radius of 5 . 00 mm and is 25 . 0 cm long
Thepotemich [5.8K]

Answer:

1.1775 x 10^-3 m^3 /s

Explanation:

viscosity, η = 0.250 Ns/m^2

radius, r = 5 mm = 5 x 10^-3 m

length, l = 25 cm = 0.25 m

Pressure, P = 300 kPa = 300000 Pa

According to the Poisuellie's formula

Volume flow per unit time is

V=\frac{\pi \times Pr^{4}}{8\eta l}

V=\frac{3.14 \times 300000\times \left ( 5\times 10^{-3} \right )^{4}}{8\times 0.250\times 0.25}

V = 1.1775 x 10^-3 m^3 /s

Thus, the volume of oil flowing per second is 1.1775 x 10^-3 m^3 /s.

3 0
3 years ago
Other questions:
  • Help please me please
    14·1 answer
  • A 60.0 kg girl stands up on a stationary floating raft and decides to go into shore. She dives off the 180 kg floating raft with
    6·1 answer
  • What is the gravitational potential energy of a book with a mass of 0.30 kg on a 1.0 m high desk?
    7·2 answers
  • Why Venus is known as red planet?​
    13·2 answers
  • What statement used during the scientific method is falsifiable or framed in a way that allow other scientist to prove it false
    8·1 answer
  • What is newtons 4th law
    6·1 answer
  • How does the electric force between two charged objects change when the
    7·1 answer
  • How long will it take a plane to fly 1256km<br> if it travels 500km/hr?
    11·1 answer
  • How Many displacement vectors shown in the figure above have horizontal components
    9·1 answer
  • A(n) what moves the medium in the same direction as the wave travels.
    15·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!