A 1.8 m tallman stand in an elevator accelerating upward at 12 m/s?,

what is the blood pressure in the brain and foot.

Take the height difference between the heart and the brain to be

0.35 m?

13.3 x 103 Pa] & [Pblood = 1060 kg.m-3]

Note: [: P Heart

Answer:

Why do metals conduct heat so well? The electrons in metal are delocalised electrons and are free moving electrons so when they gain energy (heat) they vibrate more quickly and can move around, this means that they can pass on the energy more quickly.

Answer:

A Impulse = – 25 Ns

B. Time = 5 s

Explanation:

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

Mass (M) = 5 Kg

Initial velocity (u) = 8 m/s

Final velocity (v) = 3 m/s

Impulse (I) =?

Time (t) =?

A. Determination of the Impulse.

Mass (M) = 5 Kg

Initial velocity (u) = 8 m/s

Final velocity (v) = 3 m/s

Impulse (I) =?

I = Ft = M(v – u)

I = M(v – u)

I = 5 (3 – 8)

I = 5 × – 5

I = – 25 Ns

NOTE: the negative sign indicates that the net force is acting in the negative direction.

B. Determination of the time.

Impulse (I) = 25 Ns

Force (F) = 5 N

Time (t) =?

I = Ft

25 = 5 × t

Divide both side by 5

t = 25 / 5

t = 5 s

Thus, it will take 5 s for the box to slide through the 15 m long ramp.

Answer:

Explanation:

Note the charge balls on the top and bottom row are identical. So those charges cancel each other out. The only charges in the net electric field are the two in the middle row.

Electric field strength = k*Q/r^2

= (8.99 *10^9) * (3-(-3)) * 5*10^(-6) / (2*0.5)^2

= 269700 N/C

Answer:

Explanation:

(b) cuz the 1st n 3nd row cancel out, net electric field will go from +3Q to -3Q. the direction is right.

Answer:

Option E:

The mantle

Explanation:

The earth's mantle is the mushy, semi-solid portion of the earth that makes up most of the earth's volume. The mantle extends for a depth of about 2800km downwards into the earth, making it the largest internal portion of the earth.  It makes up about 84 percent of the earth's structure, leaving the core and the crust with 15 percent and 1 percent respectively.

Due its nature, convection currents are set up predominantly in the mantle of the earth, which leads to movements in the upper layers of the earth (the crust).

The mantle is large enough for the lighter crust to float on its surface.

Answer:

a) The ideal speed = 16.21 m/s

b) Minimum co-efficient of friction = 0.216

Explanation:

From the given information:

The ideal speed can be determined by considering the centrifugal force component and the gravity component.

[tex]\dfrac{mv^2}{r}cos \theta = mg sin \theta[/tex]

[tex]v = \sqrt {gr \ tan \theta}[/tex]

[tex]= \sqrt{(9.8 \ m/s^2) (100) \ tan 15^0}[/tex]

= 16.21 m/s

(b)

Let assume that it requires 25 km/h to take the same curve.

Then, using the equilibrium conditions;

[tex]mg \ sin \theta = \dfrac{mv^2}{r} cos \theta + \mu ((\dfrac{mv^2}{r}) sin \theta + mg cos \theta)[/tex]

[tex]\mu = \dfrac{mg sin \theta - \dfrac{mv^2}{r} cos \theta }{((\dfrac{mv^2}{r}) sin \theta + mg cos \theta) }[/tex]

[tex]\mu = \dfrac{g sin \theta - \dfrac{ v^2}{r} cos \theta }{((\dfrac{v^2}{r}) sin \theta + g cos \theta) }[/tex]

[tex]\mu = \dfrac{(9.8 \ m/s^2 ) sin (15^0) - \dfrac{ \dfrac{(25 \times 10^3}{3600} \ m/s)^2 }{100 \ m } cos (15^0) }{((\dfrac{(\dfrac{25 \times 10^3}{3600} )^2}{100}) sin 15^0 + (9.8 \ m/s^2) cos 15^0 ) }[/tex]

[tex]\mathbf{\mu = 0.216}[/tex]

Doppler ultrasound would be most useful in detecting a blockage in a heart artery.

By monitoring the rate of change in pitch, a Doppler ultrasound may calculate how quickly blood flows (frequency). A sonographer with training in ultrasound imaging applies pressure to your skin with a tiny, hand-held instrument (transducer) roughly the size of a bar of soap across the area of your body being scanned, moving from one place to another as required.

As an alternative to more invasive treatments like angiography, which involves injecting dye into the blood arteries to make them visible on X-ray images, this test may be performed.

Your doctor may use a Doppler ultrasound to assess for artery damage or to keep track of specific vein and artery therapies.

Learn more about  Doppler technology here:

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Answer:

6kg

Explanation:

According to conservation of kinetic energy

m1u1+m2u2 = (m1+m2)v

m1 and m2 are the masses of the bodies

u1 and u2 are the initial velocities

v is the final velocity

Given

m1 =2kg

u1 = 8.0m/s

m2 = ?

u2 = 0m/s (second ice at rest)

v = 2.0m/s

Substitute into the formula

2(8)+m2(0) = (2+m2)(2)

16+0 = 4+2m2

16-4= 2m2

12 = 2m2

m2 =12/2

m2 = 6kg

Hence the mass of the second block is 6kg

Answer:

the answer is b luv .

Explanation:

i'm stuck on that question also

Answer:let initial velocity u=14m/s

Final velocity v=20m/s

Time taken t=30

Acceleration =a

V=u +at

a= (20-14)/30

a=0.2m/s^2

Explanation:

Acceleration is the change in velocity with respect to time.

Answer:

12

Explanation:

Answer:

V = 4.49 m/s

Explanation:

Given that,

Mass of the car 1, m₁ = 1141 kg

Initial speed of car 1, u₁ = 16 m/s

Mass of car 2, m₂ = 2916 kg

Initial speed of car 2, u₂ = 0

We need to find the speed of the cars if they stick together. Let the speed be V. The momentum will remain conserved in the process. Using the conservation of momentum to find it.

m₁u₁ + m₂u₂ = (m₁+m₂)V

[tex]V=\dfrac{m_1u_1+m_2u_2}{(m_1+m_2)}\\\\=\dfrac{1141\times 16+2916 \times 0}{(1141 +2916 )}\\\\=4.49\ m/s[/tex]

So, the required speed of the two cars is 4.49 m/s.

Answer:

4.92°

Explanation:

The banking angle θ = tan⁻¹(v²/rg) where v = designated speed of ramp = 30 mph = 30 × 1609 m/3600 s = 13.41 m/s, r = radius of curve = 700 ft = 700 × 0.3048 m = 213.36 m and g = acceleration due to gravity = 9.8 m/s²

Substituting the variables into the equation, we have

θ = tan⁻¹(v²/rg)

= tan⁻¹((13.41 m/s)²/[213.36 m × 9.8 m/s²])

= tan⁻¹((179.8281 m²/s)²/[2090.928 m²/s²])

= tan⁻¹(0.086)

= 4.92°

Answer: The bones won't fracture.

Explanation: Stress, in Physics, is a quantity describing forces that can cause deformation. Strain is the measure of how muc an object can be stretched or deformed. The ratio between stress and strain is called Young's modulus or elastic modulus

Breaking Stress of Bone is the maximum stress a bone can take before a rupture occur.

To determine if a person will break his/her bones by jumping from a height, we determine the energy necessary for that jump and compare it with the energy necessary to break a bone.

The energy for breaking a bone is calculated as

[tex]E=\frac{Al_{0}\sigma_{B}^{2}}{2Y}[/tex]

A is the area in m²

l₀ is length in m

[tex]\sigma_{B}[/tex] is breaking stress in N/m²

Y is Young's modulus in N/m²

Calculating energy to break a bone:

[tex]E=\frac{4.10^{-4}.7.10^{-1}.(1.5.10^{8})^{2}}{2.(1.5.10^{10})}[/tex]

[tex]E=210[/tex] J

This is the energy necessary to break one leg bone, so as there are 2, energy will be 420 Joules.

Potential energy gained by jumping is calculated as

E = m.g.h

m is mass in kg

g is acceleration due to gravity in m/s²

h is height in m

Calculating

E = 80.(9.8)(0.3)

E = 235.2 J

Comparing the two energies, potential energy for jumping is less than maximum energy a bone can absorve without breaking, so the leg bones won't suffer a fracture.

Answer:

P = 1471500 [Pa]

Explanation:

We must remember that pressure is defined as the relationship between Force over the area.

[tex]P=F/A[/tex]

where:

P = pressure [Pa] (units of pascals)

F = force [N] (units of Newtons)

A = area of contact = 4 [cm²]

But first we must convert from cm² to m²

[tex]A = 4[cm^{2}]*\frac{1^{2} m^{2} }{100^{2} cm^{2} }[/tex]

A = 0.0004 [m²]

Also, the weight should be calculated as follows:

[tex]w = m*g[/tex]

where:

m = mass = 60 [kg]

g = gravity acceleration = 9.81 [m/s²]

Now replacing:

[tex]w = 60*9.81\\w = 588.6[N][/tex]

And the pressure:

[tex]P=588.6/0.0004\\P=1471500 [Pa][/tex]

Because 1 [Pa] = 1 [N/m²]

Wavelength is the distance between identical points (adjacent crests) in the adjacent cycles of a waveform signal propagated in space or along a wire. In wireless systems, this length is usually specified in meters (m), centimeters (cm) or millimeters (mm).

Hope this helped

Answer:

A, B, D, and H

Explanation:

Statements A, B, D and H are all correct except the following:

Statement C is incorrect. The name of [tex] AlF_3 [/tex] is aluminium fluoride NOT "trialuminium fluoride".

Statement E is incorrect. The name of [tex] Li_2Se [/tex] is lithium selenide NOT "lithium selenate".

Statement F is incorrect. Dinitrigen monoxide, also known as nitrous oxide has a formula of [tex] N_2O [/tex] NOT [tex] NO_2 [/tex].

Statement G is incorrect. Sulfur trioxide formula is [tex] SO_3 [/tex].

Answer:

2A

Explanation:

Given parameter:

Quantity of charge  = 2C

Time taken = 1s

Unknown:

The current passing through the ring = ?

Solution:

Current can also be defined as the quantity of charge that passes  through a conductor per unit of time:

         I  = [tex]\frac{q}{t}[/tex]  

 So;

          I  = [tex]\frac{2}{1}[/tex]   = 2A

Answer:

1.25 m

Explanation:

This is the vertical height not the distance along the slope.

[tex]K=U\\\frac{1}{2}mv^{2} = mgh\\h = \frac{v^{2}}{2g}=\frac{25}{20}=1.25 m[/tex]

The height the car can reach if the the track starts to climb upwards is 1.2742 meters up.

Kinetic energy is energy possessed by a body by virtue of its movement. Potential energy is the energy possessed by a body by virtue of its position or its relation with its surrounding systems.

P.E. = mass × g × height

K.E. = 0.5 × mass × (velocity)²

Given that the toy car has a mass of 0.025 kg and is traveling on a horizontal track with a velocity of 5 m/s. Now, the car starts to climb up vertically, therefore, the kinetic energy will be converted to potential energy.

Kinetic Energy = Potential Energy

0.5 × mass × (velocity)² = mass × g × height

Cancel mass from both the sides,

0.5 × (velocity)² = g × height

0.5 × (5 m/s)² = 9.81 m/sec² × height

height = 1.2742 meters

Hence, the car will travel 1.2742 meters up.

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Answer:

The dryer sheet is negatively charged and your hand is positively charged

Explanation:

Answer:

Number of revolutions = 20.71 rev.

Explanation:

Given the following data;

Initial speed, u = 0m/s

Final speed, v = 9.9m/s

Time, t = 11.4secs

Diameter = 86.9cm to meters = 86.9/100 = 0.869m

To find the acceleration;

Acceleration, a = (v - u)/t

Acceleration, a = (9.9 - 0)/11.4

Acceleration, a = 9.9/11.4

Acceleration, a = 0.87m/s²

Now we would find the distance covered by the tire using the second equation of motion.

S = ut + ½at²

S = 0(11.4) + ½*0.87*11.4²

S = 0 + 0.435*129.96

S = 56.53m

The circumference of the tire is calculated using the formula;

Circumference = 3.142 * diameter

Circumference = 3.142 * 0.869

Circumference = 2.73m

Number of revolutions = distance/circumference

Number of revolutions = 56.53/2.73

Number of revolutions = 20.71 rev.

Therefore, the number of revolutions the tire makes during this motion is 20.71 revolutions.

Answer:

The speed when the box reaches a point 10 cm from the equilibrium position is 2.02 m/s.

Explanation:

Mass attached to the spring, m = 10 kg

maximum displacement of the spring, A = 0.44 m

The spring constant is calculated from Hook's law;

F = kx

mg = kx

k = (mg) / x

k = (10 x 9.8) / 0.44

k = 222.73 N/m

The angular speed of the spring is calculated as;

[tex]\omega = \sqrt{\frac{k}{m} } \\\\\omega =\sqrt{\frac{222.73}{10} } \\\\\omega = 4.72 \ rad/s[/tex]

The speed when the box reaches a point 10 cm from the equilibrium position is calculated as;

[tex]v = \omega \sqrt{A^2-x^2} \\\\v = 4.72\sqrt{0.44^2-0.1^2}\\\\v = 2.02 \ m/s[/tex]

Therefore, the speed when the box reaches a point 10 cm from the equilibrium position is 2.02 m/s.

Answer:

45

Explanation:

Answer:

F = 5.17 N

Explanation:

       [tex]F =\sqrt{F_{1} ^{2} +F_{2} ^{2} + 2*F_{1} * F_{2} * cos \theta} (1)[/tex]

       [tex]F =\sqrt{2.81 N ^{2} +2.81 N ^{2} + 2*2.81N* 2.81N* cos 46} = 5.17 N (2)[/tex]

Answer:

2.50 s

Explanation:

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

Initial velocity (u) = 20 m/s

Acceleration (a) = 6 m/s²

Final velocity (v) = 35 m/s

Time (t) =?

Thus, we can obtain the time taken for the man to reach a speed of 35 m/s as follow:

v = u + at

35 = 20 + 6t

Collect like terms

35 – 20 = 6t

15 = 6t

Divide both side by 6

t = 15/6

t = 2.50 s

Thus, it will take the man 2.50 s to reach a speed of 35 m/s.

Answer:

the velocity of the egg the instant before impact is 17.15 m/s.

Explanation:

Given;

mass of the egg, m = 80 g = 0.08 kg

height through which the egg was dropped, h = 15 m

The velocity of the egg before impact will be maximum, and the final velocity is given by the following kinematic equation;

v² = u² + 2gh

where;

u is the initial velocity of the egg = 0

v is the final velocity of the egg before impact

v² = 0 + 2 x 9.8 x 15

v² = 294

v = √294

v = 17.15 m/s

Therefore, the velocity of the egg the instant before impact is 17.15 m/s.

Answer:

if we are to go by the first law of thermodynamics, the Inventors claims are not reasonable.

The inventor has developed a perpetual-motion machine { any device that violates the first law of thermodynamics}

Explanation:

Given that;

energy supplied to a room Qh= 1.2 kWh

for each for each kWh of electricity it consumes, i.e work input W = 1 kWh

W know that; the first law of thermodynamics says energy can neither be created nor destroyed but can flow from one body to another;

which means ∑Q should or must be equal to ∑W;  ∑Q = ∑W

but in the given system; Qh⇒1.2 kWh is NOT equal to W⇒1 kWh

i.e Qh⇒1.2 kWh ≠ W⇒1 kWh

which simply means his device create energy and that violate the first law of thermodynamics.

Therefore, if we are to go by the first law of thermodynamics, the Inventors claims are not reasonable.

The inventor has developed a perpetual-motion machine { any device that violates the first law of thermodynamics}

Answer:

The new force between them is increased by a factor of 16.

Explanation:

According to Coulombs law, the force of attraction between two (2) charges is given by the formula;

F = Kq1q2/r²

Given the following data;

q1 = 2q1

q2 = 2q2

r = r/2

Substituting into the equation, we have;

F = 2q1*2q2/(r/2)²

F = 4q1q2/r²/4

F = 4q1q2 * 4/r²

F = 16q1q2/r²

Therefore, the new force between them is increased by a factor of 16.