What is the minimum value of the friction coefficient between the boxes that will keep them from slipping when the 100 N force is applied

Answer:

According to the data, factors influencing mining investment in South Africa's favour are the availability of labour and skills, the quality of the country's infrastructure, the quality of its geological database, and the State's environmental regulations.

Answer: The correct answer is a) 3200 m, [tex]-2m/s^2[/tex]

Explanation:

Speed is defined as the ratio of distance travelled to the time taken. The equation follows:

[tex]\text{Speed}=\frac{\text{Distance travalled}}{\text{Time taken}}[/tex]

From the graph:

Speed for the first 40 s, v = 80 m/s

Time taken, t = 40 s

Putting values in above equation, we get:

[tex]\text{Distance travalled}=(80 m/s\times 40s)=3200 m[/tex]

Acceleration is defined as the ratio of change of velocity to the change of time. The equation follows:

[tex]\text{Acceleration}=\frac{\Delta v}{\Delta t}=\frac{v_2-v_1}{t_2-t_1}[/tex]

From the graph, for the last 40 sec:

Initial velocity, [tex]v_1[/tex] = 80 m/s

Final velocity, [tex]v_2[/tex] = 0 m/s

Initial time, [tex]t_1[/tex] = 40 s

Final time, [tex]t_2[/tex] = 80 s

Putting values in above equation, we get:

[tex]\text{Acceleration}=\frac{(0-80)m/s}{(80-40)s}\\\\\text{Acceleration}=\frac{-80m/s}{40s}=-2m/s^2[/tex]

Hence, the correct answer is a) 3200 m, [tex]-2m/s^2[/tex]

Answer:

45 m

Explanation:

From the question given above, the following data were obtained:

Initial velocity (u) = 30 m/s

Deceleration (a) = –10 m/s²

Final velocity (v) = 0 m/s

Distance (s) =?

The distance of the dog from the car before the driver hits the brake can be obtained as follow:

v² = u² + 2as

0² = 30² + (2 × –10 × s)

0 = 900 + (–20s)

0 = 900 – 20s

Collect like terms

0 – 900 = –20s

–900 = –20s

Divide both side by –20

s = –900 / –20

s = 45 m

Therefore, the dog was 50 m away when the driver first hit the brake

Answer:

Explanation:

The difference between step-up and step-down transformer is given below:-

Step-up transformer  

i) It increases the voltage.

ii) It decreases the current strength.

iii) It has a greater number of turns in secondary as compared to the primary.

iv) The wire of primary is thicker than that of the secondary coil.

Step-down transformer

i) It decreases the voltage.

ii) It increases the current strength of the secondary.

iii) It has less number of turns in secondary as compared to the primary.

iv) The wire of the secondary coil is thicker than that of the primary coil.

Answer:

The free electrons tend to Negatively Charged body to Positively Charged body

Explanation:

As they have different charges, Electrons are more attracted to the Positive or it's opposite charge.

Answer:

130 dB

Explanation:

The equation for decibel level is given by:

[tex]D=10log(\frac{I}{I_n} )\\\\Where\ D\ is\ the \ decibel\ level\ in\ dB, I\ is\ the\ intensity\ in \ W/m^2, \\I_n\ is\ threshold\ intensity\ to\ the\ human\ ear=1*10^{-12}W/m^2\\\\Given\ that\ D=125dB, hence:\\\\125=10log(\frac{I}{1*10^{-12}} )\\\\12.5=log(\frac{I}{1*10^{-12}} )\\\\I=3.2\ W/m^2[/tex]

The intensity for 1 jack hammer is 3.2 W/m², therefore for 3 jack hammers, the intensity = 3 * 3.2 = 9.6 W/m²

[tex]D=10\ log(\frac{I}{I_n} )\\\\D=10*log(\frac{9.6}{1*10^{-12}} )\\\\D=130\ dB[/tex]

Answer: • Conduction only warms the shallow layer of air within a few centimeters of the ground

• Atmospheric gases do not readily absorb solar radiation

• Condensation of water vapor plays a role in heating the lower atmosphere.

• Convection distributes heat vertically

Explanation:

The statements regarding the warming of the troposphere that are true include:

• Conduction only warms the shallow layer of air within a few centimeters of the ground

• Atmospheric gases do not readily absorb solar radiation

• Condensation of water vapor plays a role in heating the lower atmosphere.

• Convection distributes heat vertically.

Therefore, the correct options are A, C, E and G.

• Conduction only warms the shallow layer of air within a few   centimeters of the ground

• Atmospheric gases do not readily absorb solar radiation

• Condensation of water vapor plays a role in heating the lower atmosphere.

• Convection distributes heat vertically

The lowest layer of the atmosphere of the earth is the troposphere. Most of the mass (about 75-80%) of the atmosphere is in the troposphere.

Most types of clouds are found in the troposphere, and almost all weather occurs within this layer.

The statements regarding the warming of the troposphere that are true include:

• Conduction only warms the shallow layer of air within a few centimeters of the ground

• Atmospheric gases do not readily absorb solar radiation

• Condensation of water vapor plays a role in heating the lower atmosphere.

• Convection distributes heat vertically.

Thus a,c,e,g are the correct statements regarding the warming of the troposphere

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Answer:

The period the field must be reduced to zero is 9.81 x 10⁻⁵ s

Explanation:

Given;

initial value of the magnetic field, B₁ = 0.276 T

number of turns of the solenoid, N = 517 turns

diameter of the solenoid, d = 10.5 cm = 0.105 m

induced emf, = 12.6 kV = 12,600 V

when the field becomes zero, then the final magnetic field value, B₂ = 0

The induced emf is given by Faraday's law;

[tex]emf = -\frac{NA\Delta B}{t} \\\\emf = -\frac{NA (B_2 -B_1)}{t} \\\\t = -\frac{NA (B_2 -B_1)}{emf}\\\\t = \frac{NA (B_1 -B_2)}{emf}\\\\where;\\\\t \ is \ the \ time \ when \ B = 0 \ \ (i.e\ B_2 = 0)\\\\A \ is \ the \ area \ of \ the \ coil\\\\A = \frac{\pi d^2}{4} = \frac{\pi (0.105)^2}{4} = 0.00866 \ m^2\\\\t= \frac{(517) \times (0.00866)\times (0.276 -0)}{12,600}\\\\t = 9.81 \times 10^{-5} \ s[/tex]

Therefore, the period the field must be reduced to zero is 9.81 x 10⁻⁵ s

Answer:

Explanation:

From the given information:

The torque produced due to the force can be expressed as:

[tex]\tau = F \times r[/tex]

where;

[tex]\tau[/tex] = torque

F = force exerted

r = lever's arm radius

[tex]\tau[/tex] = [tex]2.00 \times 10^3 \times 0.03 m[/tex]

[tex]\tau[/tex] = 60 N.m

However, equating the torque with the moment of inertia & angular acceleration, we use the equation:

[tex]\tau[/tex] = I∝

60 Nm = I × 120 rad/s²

I = 60 Nm/120 rad/s²

I = 0.5 kg.m²

Answer:

[tex]m=42\ fringes[/tex]

Explanation:

From the question we are told that:

Wavelength [tex]\lambda=400nm[/tex]

Length of cell arm [tex]h=3.70cm[/tex]

Refraction of air at  at 1.00 atm pressure [tex]n=1.00028.[/tex]

Generally the equation for Number of shifts is mathematically given by

[tex]m=N-N_o[/tex]

Since

[tex]N_0=\frac{2t}{\lambda_0}[/tex]

Therefore

[tex]m=\frac{2t}{\lambda_0/n}-\frac{2t}{\lambda_0}[/tex]

[tex]m=\frac{2t}{\lambda_0} n-1[/tex]

[tex]m=\frac{2(3.7*10^{-2})}{400*10^{-9}}*(1.00028-1)[/tex]

[tex]m=51.8[/tex]

[tex]m=42\ fringes[/tex]

Answer:

Copper would experience induced magnestism mostly easily.

Explanation:

Permalloy would experience induced magnetism most easily.

I don't know the options but that is correct too!!

Answer: A nucleus that absorbs at [tex]11.45\delta[/tex] is less shielded and a nucleus that absorbs at [tex]4.13\delta[/tex] will require a stronger applied field

Explanation:

While interpreting the data in NMR, the positions of signals are studied.

The nucleus/ protons having a higher value of [tex]\delta[/tex] are said to be less shielded. They are said to be upfield.

The nucleus/protons having a lower value of [tex]\delta[/tex] are said to be more shielded. They are said to be downfield.

So, a nucleus that absorbs at [tex]11.45\delta[/tex] is less shielded by the nucleus that absorbs at [tex]4.13\delta[/tex]

Also, the less shielded nucleus/protons will require a weak applied field to come into resonance than the more shielded nucleus/protons

So, a nucleus that absorbs at [tex]4.13\delta[/tex] will require a stronger applied field to come into resonance than the nucleus that absorbs at [tex]11.45\delta[/tex]

Answer:Solution to 47E Step 1 Angular velocity of the swing=32rpm Weight of the seat =255N Weight of the person =825N Total weight =255+825=1080N Radius =7.5m

Explanation:

Answer:

B.

Explanation:

If both train A and train B are moving in the same direction and the exact same speed then from an observer's viewpoint within either train everything would seem as though it is not moving. Therefore, the clock on train B would appear to be the same width and to run at the same rate. In order for this to be the case the speed of both trains would need to be exactly the same, any difference in speed will cause the clock on the opposite train to appear distorted and run either faster or slower depending on the speed of the train you are on.

Answer:

The trains are moving at the same speed, so the answer is A.

Answer:

The area directly above the light bulb is warmest because of convection.

Explanation:

if all the sides of the bulb are equally close to the light source inside the bulb, all area of the bulb would be equally heated by conduction. however, convection heating mainly heats up the surface above the light source. in convection heating, the air above the surface of the light source get heated by the light source and expands, casuing it to be less dense and rise to the top of the bulb. colder denser air at the top of the bulb sink to the light source adn gain heat and expands, becoming less dense. this process repeats and the surface above the light source becomes the warmest due to convection heating

it's a form of government where people elect their representatives

Answer:

The word democracy itself means rule by the people.

Answer:

The velocity after 1.5 s is 22.7 m/s downwards.

Explanation:

Initial velocity = - 8 m/s

acceleration, a = - 9.8 m/s2

time, t = 1.5 s

Use first equation of motion

v = u + at

v = - 8 - 9.8 x 1.5

v = - 8 - 14.7

v = - 22.7 m/s  

Thus, the velocity after 1.5 s is 22.7 m/s downwards.

Answer:

a. None

b. Both

Explanation:

a. Which rider is traveling faster at the bottom?

Since both riders fall from the same height, h, their potential energy, U at the top equals their kinetic energy, K at the bottom.

U = mgh and K = 1/2mv²

Since U is he same for both water-slide riders, then K will be the same and thus their speed at the bottom will be the same. This is shown below.

K = U

1/2mv² = mgh

v² = 2gh

v =√(2gh) where v = speed of rider at the bottom, g = acceleration due to gravity and h = height of slide.

Since the height is the same, so their speed at the bottom is the same. So, none of the riders travels faster than the other since they have the same speed at the bottom.

b. Which rider makes it to the bottom first? Ignore friction and assume both slides have the same path length.

Since the path length of the water slides are the same and friction is neglected, both water-slide rider get to the bottom at the same time since the distance moved is the same and they both start from rest.

So, both riders make it to the bottom at the same time.

The acceleration due to gravity acts vertically downwards, and the component of gravity acceleration is larger when the slope is steeper.

Reasons:

The acceleration of the riders are due to gravity

The component acceleration due to gravity acting on a slope is a = g·sin(θ)

As the steepness of the slope increase, the angle, θ, and sin(θ) increases, therefore, the acceleration increases.

Rider A is on a slide with gentle slope, such that if the slide is flat, rider A will be stationary.

Therefore;

a. The rider that is travelling faster at the bottom is rider B

b. Given that friction is ignored, and the path have the same length to the

bottom, the rider that makes to the bottom first is the rider that is moving

faster, which is rider B

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Answer:

Explanation:

part A: C

part B: B

Answer:

a = 7.84 m / s²

Explanation:

For this exercise let's use Newton's second law

          F - fr = m a

indicate that the force is F = 609.1 N and the friction force is fr = 107.9 N and is constant

         a = [tex]\frac{F - fr}{m}[/tex]

let's calculate

          a = [tex]\frac{ 609.1 - 107.9 }{63.9}[/tex]

          a = 7.84 m / s²

Answer:

a) The atomic number decreases by 2 units

b) the atomic mass decreases by 4 units

Explanation:

An alpha particle is a helium nucleus, which is why it is made up of two positive protons and two negative neutrons, the mass of the particles is almost the same.

a) The atomic number decreases by 2 units

b) the atomic mass decreases by 4 units

Answer:

8.16 J

Explanation:

Applying,

W = ke²/2................. Equation 1

Where W = work done in stretching the spring, k = spring constant, e = extension

make k the subject of the equation

k = 2W/e²................ Equation 2

From the question,

Given: W = 4 J, e = 14 cm = 0.14 m

Substitute these values into equation 2

k = 2(4)/0.14²

k = 8/0.0196

k = 408.16 N/m

If stretchd 20 cm from its natural length,

Therefore,

e = 20 cm = 0.2 m

W = 408.16(0.2²)/2

W = 8.16 J

Answer: [tex]85.46\ kJ[/tex]

Explanation:

Given

Volume of air [tex]V=105\ m^3[/tex]

Temperature of air [tex]T=305\ K[/tex]

Increase in temperature [tex]\Delta T=0.7^{\circ}C[/tex]

Specific heat for diatomic gas is [tex]C_p=\dfrac{7R}{2}[/tex]

Energy required to increase the temperature is

[tex]\Rightarrow Q=nC_pdT\\\\\Rightarrow Q=n\times \dfrac{7R}{2}\times \Delta T\\\\\Rightarrow Q=\dfrac{7}{2}nR\Delta T\\\\\Rightarrow Q=\dfrac{7}{2}\times \dfrac{PV}{T}\times \Delta T\quad [\text{using PV=nRT}][/tex]

Insert the values

[tex]\Rightarrow Q=\dfrac{7}{2}\times \dfrac{1.01325\times 10^5\times 105}{305}\times 0.7\\ \text{Assuming air pressure to be atmospheric P=}1.01325\times 10^5\ N/m^2\\\\\Rightarrow Q=0.8546\times 10^5\\\Rightarrow Q=85.46\ kJ[/tex]

Answer:

0.94 m³/s

Explanation:

From the question given above, the following data were obtained:

Air flow (in ft³/min) = 2×10³ ft³/min

Air flow (in m³/s) =.?

Next, we shall convert 2×10³ ft³/min to m³/min. This can be obtained as follow:

35.315 ft³/min = 1 m³/min

Therefore,

2×10³ ft³/min = 2×10³ ft³/min × 1 m³/min / 35.315 ft³/min

2×10³ ft³/min = 56.63 m³/min

Finally, we shall convert 56.63 m³/min to m³/s. This can be obtained as follow:

1 m³/min = 1/60 m³/s

Therefore,

56.63 m³/min = 56.63 m³/min × 1/60 m³/s ÷ 1 m³/min

56.63 m³/min = 0.94 m³/s

Thus, 2×10³ ft³/minis equivalent to 0.94 m³/s.

the answer to the question is D

Answer:

ans: option A

Explanation:

components along x- axis is -3x and along x- axes is -2y

now use triangle law of vector addition