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4 years ago

A car with a leftward velocity and a rightward acceleration is

1 answer:

3 0

A car with leftward velocity and a rightward acceleration will move left and slowing down. Because whenever a car moves in a specific direction, then by applying an opposite acceleration or brakes won’t make its direction spontaneously in the direction of applied brakes or acceleration, but it will first slow down the car, and then make it stop due to applied brakes and then moves it in the direction of applied acceleration.

So option “B” is correct.

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A 1300-N crate rests on the floor. How much work is required to move it at constant speed (a)

kherson [118]

a) The work done is 920 J

b) The work done is 5200 J

Explanation:

In this first part of the problem, the crate is moved horizontally at constant speed.

The work required in this case is given by

$W=Fd cos \theta$

where

F is the magnitude of the force applied

d is the displacement of the crate

$\theta$ is the angle between the direction of the force and of the displacement

Here the crate is moved at constant speed: this means that the acceleration of the crate is zero, and so according to Newton's second law, the net force on the crate is zero: this means that the force applied, F, must be equal to the force of friction (but in opposite direction), so

F = 230 N

The displacement is

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied horizontally. Therefore, the work done is

$W=(230)(4.0)(cos 0^{\circ})=920 J$

In this case, the crate is moved vertically. The force that must be applied to lift the crate must be equal to the weight of the crate (in order to move it a constant speed), therefore

F = W = 1300 N

The displacement this time is again

d = 4.0 m

And the angle is $\theta=0^{\circ}$ , since the force is applied vertically, and the crate is moved also vertically. Therefore, the work done on the crate this time is

$W=(1300)(4.0)(cos 0^{\circ})=5200 J$

Learn more about work:

brainly.com/question/6763771

brainly.com/question/6443626

#LearnwithBrainly

4 0

3 years ago

A spring with a pointer attached is hanging next to a scale marked in millimeters. Three different packages are hung from the sp

SOVA2 [1]

solution;

$the expression for force applied on the spring due to the load is\\f=k\Delta x\\here,\Delta x is the extension in the spring due to appling force\\given three case as following\\110N=k(40-x_{o})----------1\\240N=k(60-x_{o})----------2\\w=k(30-x_{o})-------------3\\$ $To calculate the accrual length of the spring,solve th equation 1 and 2\\\frac{110N}{240N}=\frac{k(40-x_{o})}{k(60-x_{o})}\\0.458=\frac{k(40-x_{o})}{k(60-x_{o})}\\0.458(60mm-x_{o})=(40mm-x_{o})\\x_{o}(1-0.458)=(40-60(0.458))mm\\x_{o}\frac{12.52}{0.542}\\=23.1mm\\to calculate the force on the spring in case,\\solve the equation 1 and 2\\\frac{110}{w}=\frac{k(40-x_{o})}{k(60-x_{o})}\\\frac{110}{w}=\frac{(40mm-23.1mm)}{30mm-23.1mm}\\w=\frac{110}{2.45}=44.9N$

8 0

3 years ago

From a window 20 feet above the ground, the angle of elevation to the top of a building across the street is 78°, and the angle

Papessa [141]

The answer would be 371.16 ft.

Refer to the diagram for the scenario. The drawing is not to scale.

Notice the diagram that you will find to adjacent right triangles. All you need to do is first solve for the needed side of one triangle, by using one side.

It sounds confusing I know, but let's do this step by step.

Angle of depression is 15°.

We use this first because we do not have enough data to use the angle of elevation.

To get the adjacent side, we use the trigonometric function TOA which means:

$tan\theta= \dfrac{opposite}{adjacent}$

We use the height of the first building as our reference, so our given will be:

Opposite = 20ft

θ = 15°

Now we put that into our formula:

$tan\theta= \dfrac{opposite}{adjacent}$

$Tan15 = \dfrac{20ft}{adjacent}$

$adjacent = \dfrac{20ft}{Tan15}$

Adjacent = 74.64 ft

Angle of elevation is 78°:

Now that we have that we can solve for the height from the point of 20ft. We use the same formula, because we are looking for the opposite, given the adjacent.

$tan\theta= \dfrac{opposite}{adjacent}$

$Tan78 = \dfrac{opposite}{74.64ft}$

$(74.64ft)(Tan78) = opposite$

351.16ft = Opposite

Now that's the height from the top of the first building. To get the total height of the building we just add the 20ft.

351.16ft + 20 ft = 371.16ft

The building across the street is 371.16 ft tall.

5 0

3 years ago

Two electric motors drive two elevators of equal mass in a three-story building 10 meters tall. Each elevator has a mass of 1,00

Lady bird [3.3K]

Answer:

19620 Watt = 19.62 kWatt

Explanation:

Power output (P) is work (W) divided by time (t): P = W/t

A work (W) is a product of a force (F) and a distance (d): W = F · d

Since the force is a product of mass and acceleration: F = m · a

then work would be: W = m · a · h

P = W/t

W = m · a · h

P = m · a · h / t

We have:

P = ?

m = 1000 kg

a = 9.81 m/s² (gravitational acceleration on the Earth)

h = 10 m

t = 5s

P = m · a · h / t = 1000 kg · 9.81 m/s² · 10 m / 5 s = 19620 Watt = 19.62 kWatt

8 0

3 years ago

What is the relationship between mass, volume, and density? What is the relationship between mass, volume, and density? Density

kirza4 [7]

Answer:

A. Density is proportional to mass and inversely proportional to volume

Explanation:

Density can be defined as the property that matter has, whether solids, liquids or gases, to be compressed in a given space.

The expression that relates the density with the another values is given by,

$\rho= \frac{m}{V}$

Where,

$\rho \propto m$ (It is directly proportional to the mass of the object)

$\rho = \frac{1}{V}$ (It is inversely proportional to the volumen of the object)

Therefore density is directly proportional to the mass and inversely proportional to the volumen.

4 0

3 years ago