please help! find magnitude and direction (the counterclockwise angle with the +x axis) of a vector that is equal to a + c

Please Help! Find Magnitude And Direction (the Counterclockwise Angle With The +x Axis) Of A Vector That

Answers

Answer 1

Answer:

Option (2)

Explanation:

From the figure attached,

Horizontal component, [tex]A_x=A\text{Sin}37[/tex]

[tex]A_x=12[\text{Sin}(37)][/tex]

     = 7.22 m

Vertical component, [tex]A_y=A[\text{Cos}(37)][/tex]

    = 9.58 m

Similarly, Horizontal component of vector C,

[tex]C_x[/tex]  = C[Cos(60)]

     = 6[Cos(60)]

     = [tex]\frac{6}{2}[/tex]

     = 3 m

[tex]C_y=6[\text{Sin}(60)][/tex]

    = 5.20 m

Resultant Horizontal component of the vectors A + C,

[tex]R_x=7.22-3=4.22[/tex] m

[tex]R_y=9.58-5.20[/tex] = 4.38 m

Now magnitude of the resultant will be,

From ΔOBC,

[tex]R=\sqrt{(R_x)^{2}+(R_y)^2}[/tex]

   = [tex]\sqrt{(4.22)^2+(4.38)^2}[/tex]

   = [tex]\sqrt{17.81+19.18}[/tex]

   = 6.1 m

Direction of the resultant will be towards vector A.

tan(∠COB) = [tex]\frac{\text{CB}}{\text{OB}}[/tex]

                  = [tex]\frac{R_y}{R_x}[/tex]

                  = [tex]\frac{4.38}{4.22}[/tex]

m∠COB = [tex]\text{tan}^{-1}(1.04)[/tex]

             = 46°

Therefore, magnitude of the resultant vector will be 6.1 m and direction will be 46°.

Option (2) will be the answer.

Please Help! Find Magnitude And Direction (the Counterclockwise Angle With The +x Axis) Of A Vector That
Please Help! Find Magnitude And Direction (the Counterclockwise Angle With The +x Axis) Of A Vector That

Related Questions

An electron with a speed of 0.95c is emitted by a supernova, where cc is the speed of light. What is the magnitude of the momentum of this electron?

Answers

Answer:

2.59×10¯²² Kgm/s

Explanation:

Data obtained from the question include:

Velocity of electron = 0.95c

Momentum =?

Next, we shall determine the velocity of the electron. This can be obtained as follow:

Velocity of electron = 0.95c

Velocity of Light (c) = 3×10⁸ m/s

Velocity of electron = 0.95c

Velocity of electron = 0.95 × 3×10⁸

Velocity of electron = 2.85×10⁸ m/s

Finally, we shall determine the mometum of the electron.

Momentum is simply defined as the product of mass and velocity. Mathematically, it is expressed as:

Momentum = mass x Velocity

Thus, with the above formula, we calculate the momentum of the electron as follow:

Mass of electron = 9.1×10¯³¹ Kg

Velocity of electron = 2.85×10⁸ m/s

Momentum of electron =?

Momentum = mass x Velocity

Momentum = 9.1×10¯³¹ × 2.85×10⁸

Momentum = 2.59×10¯²² Kgm/s

Therefore, the momentum of the electron is 2.59×10¯²² Kgm/s

A -5.40nC point charge is on the x axis at x = 1.25m . A second point charge Q is on the x axis at -0.625m.
A) What must be the charge Q for the resultant electric field at the origin to be 50.0N/C in the +x direction?
B) What must be the charge Q for the resultant electric field at the origin to be 50.0N/C in the -x direction?

Answers

Answe

a)  Q = 0.820 10⁻⁹ C ,   b)  Q = -3.52 10⁻⁹ C

Explanation:

The electric field is given by the formula

         E = k q / r²

where E is a vector quantity, so it must be added as a vector

          E_total = E₁ + E₂

let's look for the two electric fields

           E₁ = k q₁ / r₁²

           E₁ = 9 10⁹  5.4 10⁻⁹ / 1.25²

           E₁ = 31.10 N / C

           E2 = k Q / r₂²

           E2 = 9 10⁹ Q / 0.625²

           E2 = 23.04 10⁹ Q N / C           (1)

now we can solve the two cases presented

a) The total field is

            E_total = 50.0 N / C towards + x

since the test charge is positive the electric field E1 points to the right in the direction of the + x axis, so the equation is

            E_total = E1 + E₂

             E₂ = E_toal - E₁

             E₂ = 50.0 -31.10

             E2 = 18.9 N /C

With the value of the electric field we can calculate the charge (Q) using equation 1

             E₂ = 23.04 10⁹ Q

              Q = E₂ / 23.04 10⁹

              Q = 18.9 / 23.04 10⁹

              Q = 0.820 10⁻⁹ C

the charge on Q is positive

b) E_total = -50.0 N / C

              E_total = E₁ + E₂

              E₂ = E_total - E₁

              E2 = -50.0 - 31.10

               E2 = -81.10 N /C

we calculate the charge

             Q = E2 / 23.04 10⁹

             Q = -81.1 / 23.04 10⁹

              Q = -3.52 10⁻⁹ C

for this case the charge is negative

A Lotus will travel 275 meters in 4.71 seconds. What is this car's average speed?

Answers

390 Because it is what it is

The average gorilla can travel 40.23 meters in 4 seconds, calculate the average speed in meters per second (m/s) 

Answers

Answer:

10.0575 m/s

Explanation:

40.23 divide by 4

Answer:

it is 10.0575 m/s

Explanation:

The average speed is calculated by total distance/total time taken. Here, the distance is 40.23 meters and time is 4 seconds.

So, average speed = 40.23/4 m/s

= 10.0575 m/s

A ball of mass m moving with speed V collides with another ball of mass 2m (e= 1/2) in a horizontal smooth fixed circular tube of radius R (R is sufficiently large R>>>d). The time after which next collision will take place is:________

Answers

Answer:

[tex]$ \frac{4\pi R}{V}$[/tex]

Explanation:

Given :

Mass of ball 1 = m

Mass of ball 2 = 2m

Since, R>>>d, the collision is head on.

Therefore, we get

[tex]$ \frac{v_1 -v_2}{V}=\frac{1}{2}$[/tex]

[tex]$ \therefore \frac{\text{velocity of seperation}}{\text{velocity of approach}}= v_1-v_2 = \frac{V}{2}$[/tex]

Relative velocity is given by V/2. So, we get the time when the masses will again collide as

[tex]$ t = \frac{2\pi R}{\frac{V}{2}}=\frac{4\pi R}{V} $[/tex]

The speed of a bus increases uniformly from
15 ms- to 60 ms in 20 seconds. Calculate
a. the average speed,
b. the acceleration,
C. the distance travelled during the entire
period The speed of a bus increases uniformly from
15 ms- to 60 ms in 20 seconds. Calculate
a. the average speed,
b. the acceleration,
C. the distance travelled during the entire
period​

Answers

Explanation:

a. For constant acceleration:

v_avg = ½ (v + v₀)

v_avg = ½ (60 m/s + 15 m/s)

v_avg = 37.5 m/s

b. a = (v − v₀) / t

a = (60 m/s − 15 m/s) / 20 s

a = 2.25 m/s²

c. x = v_avg t

x = (37.5 m/s) (20 s)

x = 750 m

which water molecules have the greatest kinetic energy

Answers

The higher the temperature the substance is, the more energy in it because the particles are moving a lot more around in it. So therefore, steam which has the highest temperature, has the greatest kinetic energy.

How does sleep affect your ability to handle stress?

Answers

Answer: Stress can adversely affect sleep quality and duration, while insufficient sleep can increase stress levels. Both stress and a lack of sleep can lead to lasting physical and mental health problems.

Explanation:

Many report that there stress increases when the length and quality of their sleep decreases. When you do not get enough sleep, 21 percent of adults report feeling more stressed.

Sleep affects your ability to handle stress because when you have more sleep you are able to think more clearly and you’re more energized and happy throughout the day.

it is easier to swim in Ocean than in a water​

Answers

Answer:

Explanation:

Ocean contains salty water which causes the object to float rather than sinking, So yes it's easy to swim in ocean than water without salt.

When charges qa, qb, and qc are placed respectively at the corners a, b, and c of a right triangle, the potential at the midpoint of the hypotenuse is 20 V. When the charge qa is removed, the potential at the midpoint becomes 15 V. When, instead, the charge qb is removed (qa and qc both in place), the potential at the midpoint becomes 12 V. What is the potential at the midpoint if only the charge qc is removed from the array of charges?

Answers

Answer:

8v

Explanation:

First we apply super position principle

Vt= v1 + v2+ v3

Remove qa

But vt= 20v

So V = v2+v3

V1= 20-15

= 5v

Remove qb

V= v1+v3

V=8v

So the potential when qa and qc are remove is the potential due to qb

Which is 8v

A certain common-emitter amplifier has a voltage gain of 100. If the emitter bypass capacitor is removed:___________.
a. The circuit will become unstable b. The voltage gain will decrease
c. The voltage gain will increase d. The circuit will become stable

Answers

Answer:

b the voltage gain will decrease

Explanation:

Q=CV

If one object (a) is moving at 60m/s^2, and the other object (b) is moving at 65m/s^2, at what time will the faster moving object be 10m ahead of the other object?

Answers

Answer:

a is moving at 60m and the other object

A paper airplane is thrown horizontally with a velocity of 20 mph. The plane is in the air for 7.63 s before coming to a standstill on the ground. What is the acceleration of the plane?

Answers

Answer:

-1.17 m/s²

Explanation:

Given:

v₀ = 20 mph = 8.94 m/s

v = 0 m/s

t = 7.63 s

Find: a

v = at + v₀

0 m/s = a (7.63 s) + 8.94 m/s

a = -1.17 m/s²

The acceleration of the plane will be:

"-1.17 m/s²".

Acceleration and Velocity

According to the question,

Velocity, v₀ = 20 mph or,

                   = 8.94 m/s

and,

                v = 0 m/s

Time, t = 7.63 s

We know the relation,

→ v = at + v₀

By substituting the values,

  0 = a × 7.63 + 8.94

7.63a = - 8.94

      a = -[tex]\frac{8.94}{7.63}[/tex]

         = - 1.17 m/s²  

Thus the response above is correct.

Find out more information about velocity here:

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4. Lead has a density of 11.5g/cmº. A rectangular block of lead measures 7cm x5cmx2cm.
a) Find the volume of the block of lead.
b) Find the mass of the block of lead

Answers

Answer:

(a) 70cm³

(b) 805 grams

Explanation:

(a) V = L×B×H

= 7cm×5cm×2cm

= 35cm×2cm

= 70cm³

(b) Mass = Volume × Density

= 70cm³ × 11.5g/cm³

= 805 grams

4. A vehicle
accelerates from
0 km/h to
100 km/h in 10 s.
What is its average
acceleration?

Answers

Answer:

Average acceleration, [tex]a=2.77\ m/s^2[/tex]

Explanation:

Given that,

Initial velocity, u = 0 km/h

Final velocity, v = 100 km/h = 27.77 m/s

Time, t = 10 s

We need to find the average acceleration of the vehicle. It is given by the change in velocity divided by time. Som,

[tex]a=\dfrac{v-u}{t}\\\\a=\dfrac{27.77-0}{10}\\\\a=2.77\ m/s^2[/tex]

So, its average acceleration is [tex]2.77\ m/s^2[/tex].

A commuter backs her car out of her garage with an acceleration of 1.40 m/s2.A) How long does it take her to reach a speed of 2.00 m/s?B) If she then breaks to a stop in 0.800 s, what is her deceleration?

Answers

Answer:

(A) 1.43secs

(B) -2.50m/s^2

Explanation:

A commuter backs her car out of her garage with an acceleration of 1.40m/s^2

(A) When the speed is 2.00m/s then, the time can be calculated as follows

t= Vf-Vo/a

The values given are a= 1.40m/s^2 , Vf= 2.00m/s, Vo= 0

= 2.00-0/1.40

= 2.00/1.40

= 1.43secs

(B) The deceleration when the time is 0.800secs can be calculated as follows

a= Vf-Vo/t

= 0-2.00/0.800

= -2.00/0.800

= -2.50m/s^2

Which of these terms is defined as the ability to cause motion or create change? A. efficiency B. energy C. force D. sound

Answers

The term that defines the ability to cause motion or create change is called force. Details about force can be found below.

What is force?

Force is the physical quantity that denotes ability to push, pull, twist or accelerate a body and which has a direction.

Force is measured in Newtons and can be calculated by multiplying the mass of the body by its acceleration.

Therefore, it can be said that the term that defines the ability to cause motion or create change is called force.

Learn more about force at: https://brainly.com/question/13191643

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Two 100kg bumper cars are moving towards eachother in oppisite directions. Car A is moving at 8 m/s and Car B at -10 m/s when they collide head on. If the resulting velocity of Car B after the collision is 8 m/s, what is the velocity of Car A after the collision

Answers

Answer:

[tex]-10 m/s[/tex]

Explanation:

When two cars collide then the momentum of two cars will remains conserved

Mass of two cars = 100 kg Speed of car A = 8 m/s Speed of car B = - 10 m/s After collision the speed of car B = +8 m/s

By momentum conservation equation

               [tex]m1v1i+m2v2i=m1v1f + m2v2f[/tex]

               [tex](100)(8)+(100)(-10)=(100v)+(100)(8)\\ v=-10 m/s[/tex]

A car stops in 120 m. If it has an acceleration of –5m/s 2 , how long did it take to stop

Answers

Answer:

t=240s

Explanation:

Distance=120m

Acceleration=-5m/s^2

v=0

Let u=x m/s

Using equation v^2-u^2=2as:-

0-x=2(-5)(120)

-x=-1200

x=1200m/s

Using now equation v=u+at:-

0=1200+-5t

5t=1200

t=240s

If a car stops at 120 meters. If it has an acceleration of –5 meters/second², then it would take  6.928 seconds to stop.

What is acceleration?

The rate of change of the velocity with respect to time is known as the acceleration of the object.

As given in the problem a car stops at 120 meters. If it has an acceleration of –5 meters/second², then we have to find out how long it would take seconds to stop.

By using the second equation of motion,

s = ut + 1/2at²

The distance traveled by car before stopping = 120 meters

acceleration =  –5 meters/second²

-120 = 0 + 0.5×( –5)t²

t² = 120/2.5

t² =48

t = 6.928 seconds

Thus, the time taken by the car before stopping would be 6.928 seconds.

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(7) A 2500 lbm car moving at 25 mi/hr is accelerated at a constant rate of 15 ft/s2 up to a speed of 50 mi/hr. What is the force and total time required?

Answers

Answer:

The  force is  [tex]F =  1164.6\  lbf[/tex]

The time is   [tex]\Delta t =  2.44 \  s[/tex]

Explanation:

From the question we are told that

  The  mass of the car is  [tex]m  =  2500 \ lbm[/tex]

   The  initial velocity of the car is [tex]u  =  25 \ mi/hr[/tex]

   The final  velocity of the car is  [tex]v  =  50 \  mi/hr[/tex]

  The acceleration is  [tex]a =  15 ft/s^2 =  \frac{15 *  3600^2}{ 5280} =  36818.2 \  mi/h^2[/tex]

   

Generally the acceleration is mathematically represented as

      [tex]a =  \frac{v-u}{\Delta t}[/tex]

=>   [tex]36818.2 =  \frac{50 - 25 }{ \Delta t}[/tex]

=>   [tex]t = 0.000679 \  hr[/tex]

converting to seconds

       [tex]\Delta t =  0.0000679 *  3600[/tex]

=>     [tex]\Delta t =  2.44 \  s[/tex]

Generally the force is mathematically represented as

        [tex]F  =  m * a[/tex]

=>      [tex]F  =  2500 *  15[/tex]

=>      [tex]F  =  37500 \ \frac{lbm *  ft}{s^2}[/tex]

Now converting to foot-pound-second we have  

         [tex]F =  \frac{37500}{32.2}[/tex]

=>        [tex]F =  1164.6\  lbf[/tex]

Public television station KQED in San Francisco broadcasts a sinusoidal radio signal at a power of 777 kW. Assume that the wave spreads out uniformly into a hemisphere above the ground. At a home 5.00 km away from the antenna,
(a) what average pressure does this wave exert on a totally reflecting surface,
(b) what are the amplitudes of the electric and magnetic fields of the wave, and
(c) what is the average density of the energy this wave carries?
(d) For the energy density in part (c), what percentage is due to the electric field and what percentage is due to the magnetic field?

Answers

Answer:

A) P = 3.3 × 10^(-11) Pa

B) Amplitude of electric field = 1.931 N/C

Amplitude of magnetic field = 6.44 × 10^(-9) T

C) μ_av = 1.65 × 10^(-11) J/m³

D) 50% each for the electric and magnetic field

Explanation:

A) First of all let's calculate intensity.

I = P_av/A

We are given;

P_av = 777 KW = 777,000 W

Distance = 5 km = 5000 m

Thus;

I = 777000/(2π × 5000²)

I = 0.00495 W/m²

Now, the average pressure would be given by the formula;

P = 2I/C

Where C is speed of light = 3 × 10^(8) m/s

P = (2 × 0.00495)/(3 × 10^(8))

P = 3.3 × 10^(-11) Pa

B) Formula for the amplitude of the electric field is gotten from;

E_max = √[2I/(εo•c)].

Where εo is the Permittivity of free space with a constant value of 8.85 × 10^(−12) c²/N.mm²

I and c remain as before.

Thus;

E_max = √[(2 × 0.00495)/(8.85 × 10^(−12) × 3 × 10^(8))]

E_max = √3.72881355932

E_max = 1.931 N/C

Formula for amplitude of magnetic field is gotten from;

B_max = E_max/c

B_max = 1.931/(3 × 10^(8))

B_max = 6.44 × 10^(-9) T

C) Formula for average density is;

μ_av = εo(E_rms)²

Now, E_rms = E_max/√2

Thus;

E_rms = 1.931/√2

μ_av = 8.85 × 10^(−12) × (1.931/√2)²

μ_av = 1.65 × 10^(-11) J/m³

D) The energy density for the electric and magnetic field is the same. So both of them will have 50% of the energy density.

A runner jumps off the ground at a speed of 16m/s. At what angle did he jump from the ground if he landed 8m away?​

Answers

Answer:lol I don’t know good qeustion

Explanation:

Explain why a Merry-Go-Round and a Ferris Wheel have a constant acceleration when they are moving?

Answers

Answer:

merry go round and Ferris wheel have a constant acceleration due to the change in direction at every point.

Answer:

A merry-go-round is accelerating. Acceleration is a change in speed, direction, or both. Even though the speed of the merry-go-round does not change, its direction constantly changes as it spins.

Explanation:

Finally, consider the expression (6.67 x 10^-11)(5.97 x 10^24)/(6.38 x 10^6)^2 Determine the values of a and k when the value of this expression is written in scientific rotation. Enter a and k, separated by commas.

Answers

Explanation:

We need to find the value of following expression :

[tex]\dfrac{(6.67 \times 10^{-11})(5.97 \times 10^{24})}{(6.38 \times 10^6)^2}[/tex]

Firstly, solving the numerator of the above expression :

[tex]=\dfrac{39.8199\times 10^{-11+24}}{40.7044\times 10^{12}}\\\\=\dfrac{39.8199\times 10^{13}}{40.7044\times 10^{12}}\\\\=9.7827[/tex]

Rounding off the result = 9.78

In scientific notation : [tex]9.78\times 10^0[/tex]

The value of a = 9.78 and k = 0.

An 85 kg skydiver is falling through the air at a constant speed of 195 km h-1. At what rate does air resistance remove energy from the skydiver?

Answers

Answer:

46041J

Explanation:

Using Energy lost= mgh

Changing to standard its we have

= 195*1000/3600=54.2m/s

So = 85*54.2*10= 46041J

Answer:

45167.15 J/s

Explanation:

mass of the man = 85 kg

The man's speed = 195 km/h = 195 x 1000/3600 = 54.167 m/s

The man's weight = mg

where

m is the mass

g is acceleration due to gravity = 9.81 m/s^2

weight = 85 x 9.81 = 833.85 N

The rate at which energy is removed from the man = speed x weight

==> 54.167 x 833.85 = 45167.15 J/s

A satellite dish has the shape of a parabola when viewed from the side. The dish is inches wide and inches deep. How far is the receiver from the bottom of the dish if the receiver is placed at the focus

Answers

Complete question is;

A satellite dish has the shape of a parabola when viewed from the side. The dish is 60 inches wide and 45 inches deep. How far is the receiver from the bottom of the dish if the receiver is placed at the focus?

Answer:

the receiver should be put 40 inches from the bottom of the dish on the concave side of the dish

Explanation:

The base of the dish would simply be the vertex of parabola.

Since we want to find how far the receiver is from the bottom, the place where we'll place the receiver is simply the focus of the parabola.

Now, for example, if this is a parabola that opens upward and has it's vertex at the origin, then half of the diameter at a height of 45 inches gives the two points (60, 22.5) and (-60, 22.5)

Standard form equation of parabola with vertex at origin and pointing upwards is given by;

x² = 4ay

Plugging in the values of x and y gives;

60² = 4a(22.5)

3600/90 = a

a = 40 inches

Thus, the receiver should be put 40 inches from the vertex on the concave side of the dish

if a cart goes around a turn at 20 km/h ,what remains constant

1.position
2.velocity
3.direction
4.speed

Answers

Answer: 4.speed

Explanation:

In this case, we know that the cart remains at a constant 20km/h.

Now, one could say that "the velocity remains constant, because it always is 20km/h"

But remember that velocity is a vector, so this has a direction, and if the cart is going around a turn, then the direction of motion is changing, which tell us that there is acceleration.

But the module of the velocity, the speed, remains constant at 20km/h.

Then the correct option is 4, speed.

The energy radiated per unit surface area (across all wavelengths) for a black body with temperature 2200. Use 5.67 x 10-8 for the Stefan-Boltzmann constant.The ____________ describes the power radiated from a black body in terms of its temperature. Specifically, the total energy radiated per unit surface area of a black body across all wavelengths per unit time is proportional to the fourth power of the black body's thermodynamic temperature

Answers

Answer:

Stefan-Boltzmann Law describes the power radiated from a black body in terms of its temperature. Specifically, the total energy radiated per unit surface area of a black body across all wavelengths per unit time is proportional to the fourth power of the black body's thermodynamic temperature

Explanation:

So we now know that

energy per unit area is = zigma x T^4

From this

T = temperature in kelvin

zigma is stefan boltzman constant

So

E/A = 5.67 x 10^-8 x (2200)⁴

= 1.33x 10^6 W/m^2

Gwen releases a rock at rest from the top of a 40-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the speed of the rock as it hits the ground?

Answers

Answer:

[tex]28\; \rm m \cdot s^{-1}[/tex].

Explanation:

Short Explanation

Apply the SUVAT equation [tex]\left(v^2 - u^2) = 2\, a \, x[/tex], where:

[tex]v[/tex] is the final velocity of the object,[tex]u[/tex] is the initial velocity of the object, [tex]a[/tex] is the acceleration (should be constant,) and[tex]x[/tex] is the displacement of the object while its velocity changed from [tex]v[/tex] to [tex]u[/tex].

Assume that going downwards corresponds to a positive displacement. For this question:

[tex]v[/tex] needs to be found.[tex]u = 0[/tex] because the rock is released from rest.[tex]a = g = 9.8 \; \rm m\cdot s^{-2}[/tex].[tex]x = 40\; \rm m[/tex].

Solve this equation for [tex]v[/tex]:

[tex]\displaystyle v = \sqrt{2\, a\, x + u^2} = \sqrt{2\times 9.8 \times 40} = 28\; \rm m \cdot s^{-1}[/tex].

In other words, the rock reached a velocity of [tex]28\; \rm m\cdot s^{-1}[/tex] (downwards) right before it hits the ground.

Explanation

Let [tex]v[/tex] be the velocity (in [tex]\rm m \cdot s^{-1}[/tex]) of this rock right before it hits the ground. Under the assumptions of this question, it would take a time of [tex]t = (v / 9.8)[/tex] seconds for this rock to reach that velocity if it started from rest and accelerated at [tex]9.8\; \rm m \cdot s^{-2}[/tex].

Note that under these assumptions, the acceleration of this rock is constant. Therefore, the average velocity of this rock would be exactly one-half the sum of the initial and final velocity. In other words, if [tex]u[/tex] denotes the initial velocity of this rock, the average velocity of this rock during the fall would be:

[tex]\displaystyle \frac{u + v}{2}[/tex].

On the other hand, [tex]u = 0[/tex] because this stone is released from rest. Therefore, the average velocity of this rock during the fall would be exactly [tex](v / 2)[/tex].

The displacement of an object over a period of time is equal to the length of that period times the average velocity over that period. For this rock, the length of this fall would be [tex]t = (v / 9.8)[/tex], while the average velocity over that period would be [tex](v / 2)[/tex]. Therefore, the displacement (in meters) of the rock during the entire fall would be:

[tex]\displaystyle \left(\frac{v}{2}\right) \cdot \left(\frac{v}{9.8}\right) = \frac{v^2}{19.6}[/tex].

That displacement should be equal to the change in the height of the rock, [tex]40\; \rm m[/tex]:

[tex]\displaystyle \frac{v^2}{19.6} = 40[/tex].

Solve for [tex]v[/tex]:

[tex]v = 28\; \rm m \cdot s^{-1}[/tex].

Once again, the speed of the rock would be [tex]28\;\rm m \cdot s^{-1}[/tex] right before it hits the ground.

A ski lift has a one-way length of 1 km and a vertical rise of 200 m. The chairs are spaced 20 m apart, and each chair can seat three people. The lift is operating at a steady speed of 10 km/h. Neglecting friction and air drag, and assuming that the average mass of each loaded chair is 250 kg, determine the power required to operate this ski lift. Also, estimate the power required to accelerate this ski lift in 17 s to its operating speed when it is first turned on.

Answers

Answer:

Explanation:

The question states that the chairs are spaced 20 m apart through a length of 1 km, or say, 1000 m.

It also does say that each chair weighs 250 kg, and as such the load is

M = 50 * 250

M = 12500.

Taking into consideration, the initial and final heights, we have

h1 = 0, h2 = 200 m

The work needed to raise the chairs,

W = mgh, where h = h2 - h1

W = 12500 * 9.81 * (200 - 0)

W = 2.54*10^7 J

The work is done at a rate of 10 km/h, and at a distance of 1 km, time taken would be

t = 1/10 = 0.1 h or say, 360 s

The power needed thus, is

P = W/t

P = 2.54*10^7 / 360

P = 68125 W, or 68 kW

Initial velocity, u = 0 m/s

Final velocity, v = 10 km/h = 2.78 m/s

Startup time, t is 17 s

Acceleration during the startup then is

a = (v - u)/t

a = 2.78/17

a = 0.163 m/s²

The power needed for the acceleration is

P = ½m [(v² - u²)/t]

P = ½ * 12500 * [2.78²/17]

P = 6250 * 0.455

P = 2844 W

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