how do positive and negative acceleration differ?

1. positive acceleration represents an object speeding up; negative acceleration represents an object slowing down

2. positive acceleration moves North or east; negative acceleration moves south or west

3. positive acceleration occurs when there is more velocity than speed; negative acceleration occurs when there is less velocity than speed.

4. positive acceleration occurs when an object changes its speed but not its direction; negative acceleration occurs when an object changes both its speed and direction​

Answer:

17⁰ north of west

Explanation:

We shall represent forces by vector notations . i will represent unit vector towards east and j will represent unit vector towards north .

Jane: 80 pounds, straight east

F₁ = 80 i

Brittany: 100 pounds, north (90 degrees relative to east)

F₂ = 100 j

Robyn: 80 pounds, southwest (225 degrees relative to east ) or 45⁰ south of west

F₃ = - 80cos 45  i - 80 sin45 j = - 80/√2 x ( i + j )

= - 40√2 ( i + j )

Scott: 100 pounds, northwest (135 degrees relative to east) or 45⁰ west of north .

F₄ = - 100 cos 45 i + 100 sin45 j =  50√2 ( - i + j )

Resultant force

= F₁ + F₂ + F₃ + F₄

F =  80 i + 100 j + - 40√2 ( i + j ) + 50√2 ( - i + j )

F = 80 i - 90√2 i + 110√2 j

80 i - 127.26 i + 114.14 j

F = - 47.26 i + 114.14 j

Direction of force

TanФ = 114.14 / 47.26 = 2.4

Ф = 67⁰

67⁰ north of west .

Answer:

C. zero for both

Explanation:

In case of solid metal sphere , when it is given any charge , all the charges are transferred on the surface and within surface no charge exists . In case of hollow metal sphere , all charges reside on surface . In this way , in both solid and hollow sphere , all charge reside on the surface and no charge resides inside it . Hence due to absence of any charge inside  , there is no electric field inside the sphere in both the cases .  

Hence in both the case electric field is zero .

option C is correct .

Option B. Visitors enter the art gallery at the same rate as other visitors leave.

Answer:

B) Visitors enter the art gallery at the same rate as other visitors

leave.

Explanation:

A.P.E.X

Answer:

(a) 1.21 m/s² (b) 1.75 m/s²

Explanation:

The initial speed of the car, u = 17.8 m/s

Case 1.

Final speed of the car, v = 23.5 m/s

Time, t = 4.68-s

Acceleration = rate of change of velocity

[tex]a=\dfrac{23.5 -17.8 }{4.68}\\\\a=1.21\ m/s^2[/tex]

Case 2.

Final speed of the car, v = 15.3 m/s

[tex]a=\dfrac{23.5 -15.3}{4.68}\\\\a=1.75\ m/s^2[/tex]

Hence, this is the required solution.

Acceleration is the change in the velocity of a body with time.

The term acceleration is the change in the velocity of a body with time. We have to find the acceleration in two separate cases;

Case 1;

a = -(23.5 m/s - 17.8 m/s)/4.68-s

a = -1.2 m/s^2

Case 2;

a = -(15.3 m/s - 17.8 m/s)/4.68-s

a = 0.53 ms-2

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Answer:

2880 N/c

Explanation:

Given that:

Charge per unit length ; λ = 4 * 10^-9

radius, r = 10

Radius, R = 0.5m

Using the relation :

2λr / 4πE0R²

Columb's constant, k = 1/4πE0 =. 9* 10^9Nm²/C²

Hence, we have :

2λrk/ R²

(2 * 4 * 10^-9 * 10 * 9 * 10^9) / 0.5^2

(720 ÷ 0.25)

= 2880 N/c

Answer:

1800 J

Explanation:

We are given that

Weightlifter hold weight, w=1500N

Height of weightlifter from ground,h=1m

Length of chain=2m

Total weight of chain, w'=400 N

We have to find the work done required to lift the barbell to height of 2m.

Total work done=Work done to lift  a barbell and half of the chain+ work done  to lift the upper half of the chain

Total work done=[tex]1500+\frac{1}{2}(400)+\frac{1}{2}(400)(\frac{1}{2}(1))[/tex]

Total work done=[tex]1700+100[/tex]

Total work done=1800 J

Hence, work done is required to lift the barbell to a height of 2 m=1800 J

Answer:

14.1seconds approx

Explanation:

Given data

Distance= 59.1m

Your velocity= 2.35m/s

Walkway velocity= 1.85m/s

Total velocity= 2.35+1.85= 4.2m/s

We know that

Velocity= distance/time

time= distance/velocity

substitute

time= 59.1/4.2

time= 14.07

time=14.1seconds approx

Hence the time is 14.1seconds approx

Answer:

Convection

Explanation:

Convection refers to the transfer of heat by the actual movement of the heated molecules from the hot parts to the cooler parts.

Thus, the two diagrams show illustrate transfer of heat by the movement of molecules of a fluid.

This mode of heat transfer is known as convection. It is the concept illustrated by both diagrams.

Answer:

It is a screw.

Explanation:

Answer:

c

Explanation:

Answer:

0.76m

Explanation:

Given data

Frequency= 230Hz

speed= 350m/s

Since we are told that the frequency is the fundamental frequency n= 1

For a standing wave

Fn= nv/2L

n= 1

230= 1*350/2*L

230= 350/2L

cross multiply

2L= 350/230

2L=1.521

L=1.521/2

L=0.76m

Hence the length is 0.76m

Answer:

A concave lens is exactly the opposite with the outer surfaces curving inward, so it makes parallel light rays curve outward or diverge. That's why concave lenses are sometimes called diverging lenses.

Answer: A concave lens

A concave lens is exactly the opposite with the outer surfaces curving inward, so it makes parallel light rays curve outward or diverge. That's why concave lenses are sometimes called diverging lenses.

Hopes this helps :)

Answer:

There is no correlation that can be made between the predator and prey populations.

Explanation:

Ermrmrm.

Answer:

120.237 seconds

Explanation:

Given that:

V = 144 V

I = 10.5 A

H = 60.6 kJ

Using the formula:

H = I²RT

From H = I²RT; making T the subject, we have:

[tex]T = \dfrac{H}{I^2R}[/tex]

where;

[tex]R = \dfrac{V}{I}[/tex]

∴

[tex]T = \dfrac{H}{V \times I}[/tex]

[tex]T = \dfrac{60.6 \times 10^3 }{144 \times 10.5}[/tex]

T = 40.079

[tex]T_{neq} = 3T[/tex]

[tex]T_{neq} =3 \times 40.079[/tex]

[tex]\mathbf{T_{neq} =120.237 \ sec}[/tex]

This question involves the concepts of compression and rarefraction.

This wave should be classified as "A) a longitudinal wave".

A surface wave is a mechanical wave which propagates on the boundary interface between two different media.

A longitudinal wave is the wave in which the direction of travel of the wave and medium are the same. This wave consists of compressions and rarefactions.

A transverse wave is the wave in which the direction of travel of the wave and medium are perpendicular to each other. It consists of crests and troughs.

An electromagnetic wave is the one which consists of electric field and magnetic field vibrating perpendicular to each other.

Hence, the wave with compressions and rarefactions is classified as a longitudinal wave.

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Answer:

Newtons 2nd Law of motion affects football as well. This law states the greater the mass of an object, the less the acceleration. This means that the more the objects weighs, the more difficult it is to move the object.

Explanation:

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Electrons are the particle pr4esent inside the atom that does not affect the stability of the atom,

The ability of some unstable atoms to emit nuclear radiation spontaneously, typically in the form of alpha or beta particles frequently accompanied by gamma rays, is known as radioactivity.

An overabundance of neutrons or protons can make the nucleus of an atom unstable.

A radioactivity atom will try to become stable by extruding other particles, such as protons or neutrons, or by releasing energy in various ways.

Thus, Electrons are the particle present inside the atom that does not affect the stability of the atom,

To learn more about radioactivity here, refer to the link;

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Answer:

a horizontal force of 120N to Push the block into the floor is called net force

Answer:

Scalar

Explanation:

A scalar quantity is a physical quantity that has magnitude but no directional attribute.

An example of a scalar is speed and distance.

A vector is a physical quantity that has both magnitude and direction.

An example is displacement and velocity.

Scalar has only the magnitude value specified and nothing else.

Answer:

Explanation:

Horizontal component of initial velocity of throw = 20 cos 53 = 12 m /s

Vertical component = 20 sin 53 = 15.97 m /s

Distance to be travelled horizontally = 6 m .

time taken by ball to travel this distance = 6 / 12 = 0.5 s

vertical displacement during this period can be calculated as follows .

Initial vertical velocity = 15.97 m /s

time of travel = .5 s

acceleration = - 9.8 m /s²

s = ut - 1/2 g t²

= 15.97 x .5 - .5 x 9.8 x 0.5²

= 7.985 - 1.225

= 6.76 m

Goal post is 6 m high , so ball will cross the goal post .76 m or 76 cm above cross bar  .

b ) vertical component of ball when it crosses the goal post . Let it be v .

v = u - gt

Applying this formula for vertical movement ,

v = 15.97 - 9.8 x .5

= 15.97 - 4.9

= 11.07 m /s .

Answer:

Tt = 70 + 135e^-0.031t

13 minutes

Explanation:

Given that :

Initial temperature, Ti = 205°

Temperature after 2.5 minutes = 195°

Temperature of room, Ts= 70

Using the relation :

Tt = Ts + Ce^-kt

Temperature after time, t

When freshly poured, t = 0

205 = 70 + Ce^-0k

205 = 70 + C

C = 205 - 70 = 135°

T after 2.5 minutes to find proportionality constant, k

Tt = Ts + Ce^-kt

195 = 70 + 135e^-2.5k

125 = 135e^-2.5k

125 / 135 = e^-2.5k

0.9259 = e^-2.5k

Take In of both sides :

−0.076989 = - 2.5k

k = −0.076989 / - 2.5

k = 0.031

Equation becomes :

Tt = 70 + 135e^-0.031t

t when Tt = 160

160 = 70 + 135e^-0.031k

90 = 135e^-0.031t

90/135 = e^-0.031t

0.6667 = e^-0.031t

In(0.6667) = - 0.031t

−0.405465 = - 0.031t

t = 0.405465/ 0.031

t = 13.071

t = 13 minutes

Answer:

Explanation:

But the reality is that: Multiple magnetic fields would fight each other. This could weaken Earth's protective magnetic field by up to 90% during a polar flip. Earth's magnetic field is what shields us from harmful space radiation which can damage cells, cause cancer, and fry electronic circuits and electrical grids.

How do magnetic poles interact? Magnetic poles that are alike repel each other, and magnetic poles that are unlike attract each other. The area of magnetic force around a magnet. The magnetic field lines spread out from the north pole, curve around, and return to the south pole.

When two magnets are brought together, the opposite poles will attract one another, but the like poles will repel one another. This is similar to electric charges. The earth is like a giant magnet, but unlike two free hanging magnets, the north pole of a magnet is attracted to the north pole of the earth.

Magnetic forces are non contact forces; they pull or push on objects without touching them. Magnets are only attracted to a few 'magnetic' metals and not all matter. Magnets are attracted to and repel other magnets.

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Answer:

27872.2 miles per hour

Explanation:

Given that :

Radius of Jupiter is approximately = 44,360 miles

Revolution is 10 hours ;

Jupiter makes one revolution in 10 hours :

Using the relation to obtain the velocity :

V = re

r = radius

w = 2π/T

Hence,

V = r * 2π/ T

V =44360 * 2 * π/10

V = 88720 * π/10

V = 278722.10 / 10

V = 27872.210

V = 27872.2 miles per hour

Answer:

the block reaches higher than the sphere

\frac{y_{sphere}} {y_block} = 5/7

Explanation:

We are going to solve this interesting problem

A) in this case a sphere rolls on the ramp, let's find the speed of the center of mass at the exit of the ramp

Let's use the concept of conservation of energy

starting point. At the top of the ramp

         Em₀ = U = m g y₁

final point. At the exit of the ramp

         Em_f = K + U = ½ m v² + ½ I w² + m g y₂

notice that we include the translational and rotational energy, we assume that the height of the exit ramp is y₂

energy is conserved

          Em₀ = Em_f

         m g y₁ = ½ m v² + ½ I w² + m g y₂

angular and linear velocity are related

        v = w r

the moment of inertia of a sphere is

         I = [tex]\frac{2}{5}[/tex] m r²

we substitute

         m g (y₁ - y₂) = ½ m v² + ½ ([tex]\frac{2}{5}[/tex] m r²) ([tex]\frac{v}{r}[/tex])²

         m g h = ½ m v² (1 + [tex]\frac{2}{5}[/tex])

where h is the difference in height between the two sides of the ramp

h = y₂ -y₁

         mg h = [tex]\frac{7}{5}[/tex] ([tex]\frac{1}{2}[/tex] m v²)

         v = √5/7  √2gh

This is the exit velocity of the vertical movement of the sphere

         v_sphere = 0.845 √2gh

B) is the same case, but for a box without friction

   starting point

          Em₀ = U = mg y₁

   final point

          Em_f = K + U = ½ m v² + m g y₂

          Em₀ = Em_f

          mg y₁ = ½ m v² + m g y₂

          m g (y₁ -y₂) = ½ m v²

          v = √2gh

this is the speed of the box

          v_box = √2gh

to know which body reaches higher in the air we can use the kinematic relations

          v² = v₀² - 2 g y

at the highest point v = 0

           y = vo₀²/ 2g

for the sphere

           y_sphere = 5/7 2gh / 2g

           y_esfera = 5/7 h

for the block

           y_block = 2gh / 2g

            y_block = h

therefore the block reaches higher than the sphere

         [tex]\frac{y_{sphere}} {y_bolck} = 5/7[/tex]

Answer:

Explanation:

The enclosure will behave as black body . For black body , the formula for radiant energy is given by Stefan's law as follows

E = σ A T⁴ where σ = 5.67 x 10⁻⁸ W m⁻² T⁻⁴

Area A = .01 m²

E = 48 W

48 = .01 x 5.67 x 10⁻⁸ T⁴

T⁴ =  846.56 x 10⁸

T= 539 K

Following are the calculation to the temperature of the interior enclosure wall:

Given:

[tex]\to A_s=50\ m^2\\\\\to A_0=0.01\ m^2\\\\\to q_{rad}=48\ w\\\\\to \sigma = 5.67 \times 10^{-8}\ \frac{W}{m^{-2} T^{-4}} \\\\[/tex]

To find:

[tex]T_s=?[/tex]

Solution:

Using the value to calculate the surface is black radiates power:

[tex]\to q_{rad}=A_0 E_0 T_s\\\\\to q_{rad}=A_0 \sigma T_{s}^4\\\\\to 48=0.01 \times 5.67 \times 10^{-8} \times T_{s}^4\\\\[/tex]

[tex]\to T_{s}^4 =\frac{48}{0.01 \times 5.67 \times 10^{-8}} \\\\[/tex]

        [tex]=\frac{48\times 100}{ 5.67 \times 10^{-8}} \\\\=\frac{48\times 100\times 10^{8} }{ 5.67 } \\\\=\frac{48\times 10^{10} }{ 5.67 } \\\\=8.46\times 10^{10} \\\\[/tex]

[tex]\to \bold{T_s=\pm 539.31 \ K}[/tex]

Therefore the final answer is "[tex]\bold{\pm 539.31 \ K}[/tex]".

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Answer:

Explanation:

We shall apply Bernoulli's formula to solve the problem . It is as follows .

P + ρ gh + 1/2 ρ v² = constant .

P₁ + ρ gh + 1/2 ρ v₁²  = P₂ + ρ gh + 1/2 ρ v₂²

P₁ +  1/2 ρ v₁²  = P₂  + 1/2 ρ v₂²

P₁ - P₂ = 1/2 ρ (v₂² - v₁² )

= .5 x 1,1 ( 30² - 20² )

= 275 N / m²

velocity over moon roof is high , pressure will be lower there by 275 N / m²

Given pressure difference already existing = 90500 - 90000 = 500 N / m²

Additional pressure difference due to velocity difference = 275 N / m²

Total pressure difference = 275 + 500 = 775 N / m²

Area of roof = .5 m²

Total force acting upwards on the roof

= .5 x 775 N

= 387.5 N .

Answer:

The energy an object has because it is moving

Explanation:

It has been a while since I have talked about kinetic energy so I can't give you an explanation why that answer is right but it is.

Answer:

1.4km/h

Explanation:

distance/time = speed

69/45=1.4km/h

Answer:

the answer is 32

Explanation:

he was riding pretty far