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lesya [120]
3 years ago
15

A block of mass 14.9 kg is pulled to the right by an applied force of 39.4 N. If it moves with constant velocity, how much frict

ion must be present?
Physics
1 answer:
lakkis [162]3 years ago
8 0

The frictional force is 39.4 N

Explanation:

We can solve this problem by applying Newton's 2nd law of motion: in fact, the net force acting on the block is equal to the product between its mass and its acceleration. So we can write

\sum F = ma

where

\sum F is the net force

m is the mass

a is the acceleration

Here we know that the box is moving with constant velocity, so its acceleration is zero:

a=0

This means that the net force is also zero:

\sum F=0

The net force on the block is given by the applied force, forward, and the frictional force, backward:

\sum F = F_a-F_f=0

where

F_a=39.4 N is the applied force

F_f is the frictional force

Therefore, solving for F_f,

F_f=F_a=39.4 N

Learn more about friction:

brainly.com/question/6217246

brainly.com/question/5884009

brainly.com/question/3017271

brainly.com/question/2235246

#LearnwithBrainly

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The sound source of a ship’s sonar system operates at a frequency of 22.0 kHz . The speed of sound in water (assumed to be at a
Degger [83]

Answer:

147.456077993 Hz

Explanation:

f_0 = Frequency of the sonar = 22 kHz

v_w = Velocity of the whale = 4.95 m/s

v = Speed of sound in water = 1482 m/s

The difference in frequency is given by

\Delta f=f_0\times\dfrac{2v_{w}}{v-v_w}\\\Rightarrow \Delta f=22000\times\dfrac{2\times 4.95}{1482-4.95}\\\Rightarrow \Delta f=147.456077993\ Hz

The difference in frequency is 147.456077993 Hz

6 0
3 years ago
An object is placed between two plain mirrors which make angle 45 degree with each other. Distance between all adjacent images a
marysya [2.9K]
I have a formula here that might just help you solve the problem on your own:

The number of images depends on the angle between the two mirrors. The number of images formed in two plane mirrors inclined at an angle A to each other is given by the formula:

Number of images = 360<span>/A - 1.
</span>
I hope my guide has come to your help. God bless and have a nice day ahead!
3 0
3 years ago
When two resistors are wired in series with a 12 V battery, the current through the battery is 0.33 A. When they are wired in pa
MA_775_DIABLO [31]

Answer:

If R₂=25.78 ohm, then R₁=10.58 ohm

If R₂=10.57 then R₁=25.79 ohm

Explanation:

R₁ = Resistance of first resistor

R₂ = Resistance of second resistor

V = Voltage of battery = 12 V

I = Current = 0.33 A (series)

I = Current = 1.6 A (parallel)

In series

\text{Equivalent resistance}=R_{eq}=R_1+R_2\\\text {From Ohm's law}\\V=IR_{eq}\\\Rightarrow R_{eq}=\frac{12}{0.33}\\\Rightarrow R_1+R_2=36.36\\ Also\ R_1=36.36-R_2

In parallel

\text{Equivalent resistance}=\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}\\\Rightarrow {R_{eq}=\frac{R_1R_2}{R_1+R_2}

\text {From Ohm's law}\\V=IR_{eq}\\\Rightarrow R_{eq}=\frac{12}{1.6}\\\Rightarrow \frac{R_1R_2}{R_1+R_2}=7.5\\\Rightarrow \frac{R_1R_2}{36.36}=7.5\\\Rightarrow R_1R_2=272.72\\\Rightarrow(36.36-R_2)R_2=272.72\\\Rightarrow R_2^2-36.36R_2+272.72=0

Solving the above quadratic equation

\Rightarrow R_2=\frac{36.36\pm \sqrt{36.36^2-4\times 272.72}}{2}

\Rightarrow R_2=25.78\ or\ 10.57\\ If\ R_2=25.78\ then\ R_1=36.36-25.78=10.58\ \Omega\\ If\ R_2=10.57\ then\ R_1=36.36-10.57=25.79\Omega

∴ If R₂=25.78 ohm, then R₁=10.58 ohm

If R₂=10.57 then R₁=25.79 ohm

6 0
3 years ago
A space traveller leaves Earth for 10 years at .85c. According to an observer on Earth, how much time has passed?
eduard
First of all, you didn't tell us WHO measured the "10 years".

If it was the people on Earth, then 10 years passed according to them.

If it was 10 years on the space traveler's clock,  then the clock in the
OTHER place, like on Earth, is subject to the relativistic 'time dilation'.

If the clocks are moving relative to each other, then the time interval measured
on either clock is equal to the interval measured on the other clock, divided by

       √(1 - v²/c²) .

You said that  v/c  = 0.85 .

v²/c² = (0.85)² = 0.7225

1 - v²/c² =  1 - 0.7225 = 0.2775

√(1 - v²/c²)  =  √0.2775 = 0.5268

If one clock counts up 10 years, then the other one counts up

(10years) / 0.5268 =  <em>18.983 years </em>


I believe that's the way to do this, and I'll gladly take your points,
but let me recommend that you get a second opinion before you
actually take off on your 10-year interstellar mission.

8 0
3 years ago
A piece of purple plastic is charged with 3. 13×106 extra electrons compared to its neutral state. what is its net electric char
horsena [70]

A piece of purple plastic is charged with 3. 13×106 extra electrons compared to its neutral state, then the net electric charge in coulomb would be - 5.008×10⁻¹³ coulombs.

<h3>What is an electric charge?</h3>

Charged material experiences a force when it is exposed to an electromagnetic field due to the physical property of electric charge. You can have a positive or negative electric charge (commonly carried by protons and electrons respectively). Unlike charges attract one another while like charges repel one another. We refer to an object as neutral if it has no net charge.

The charge on one electron is -1.6 ×10⁻¹⁹ coulomb.

Then the charge on the 3.13×10⁶ extra electrons compared to its neutral state

=-1.6×10⁻¹⁹ ×(3.13×10⁶)

As given in the problem A piece of purple plastic is charged with 3.13×10⁶ extra electrons compared to its neutral state then the net electric charge in coulombs would be - 5.008×10⁻¹³ coulombs.

Learn more about an electric charge from here

brainly.com/question/8163163

#SPJ4

4 0
2 years ago
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