The driver of a 3000 lb. car, coasting down a hill, sees a red light at the bottom, and must stop. His speed when he applies the brakes is 60 mph, and he is 100 feet (vertically) above the bottom of the hill. (a)How much energy as heat must be dissipated by the brakes if we neglect wind resistance and other frictional effects

Answer:

i think its ancestor

Explanation:

sry if im wrong

Answer:

scientists compare organisms DNA to support the theory that all species share a common Ancestor.

Answer:

the speed of the mass when it is halfway to the equilibrium position is 1.26 m/s

Explanation:

Given that;

mass of the object m = 1.20 kg

period of oscillation = 0.750 s

Amplitude ( A/x) = 15.0 cm = 0.15 m

now;

a) Determine the oscillation frequency;

oscillation frequency f = 1/T

we substitute

f = 1 / 0.750 s

f = 1.33 Hz

Therefore, the oscillation frequency is 1.33 Hz

b) Determine the spring constant;

we solve for spring constant from the following expression;

T = 2π√(m/k)

k = 4π²m / T²

so we substitute

k = (4π² × 1.20) / (0.750)²

k = 47.3741 / 0.5625

k =  84.22 N/m

Therefore, the spring constant is 84.22 N/m

c) determine the speed of the mass when it is halfway to the equilibrium position

So, at equilibrium, the energy is equal to K.E

such that;

1/2mv² = 1/2kx²

mv² = kx²

v² = kx² / m

v = √( kx²/m)

we substitute

v = √( 84.22×(0.15 m)²/ 1.2 )

v = √( 1.89495 / 1.2 )

v = √ 1.579125

v = 1.26 m/s  

Therefore, the speed of the mass when it is halfway to the equilibrium position is 1.26 m/s

Answer:

While working as a staff physicist at hughes Research Laboratories McNair learned that the National Aeronautics and Space Administration (NASA) was looking for scientist to join the shuttle program;)

Answer:

b

Explanation:

because a elastic band uses elastic energy

Answer:

a required or allowed amount, especially an amount of money legally payable in damages.

OR

In physics it means a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents.

Explanation:

Answer:

I do believe her actions were justified.

Explanation:

Due to the school charging extra fee from her father who makes a modest amount as a teacher. There was sum of money involved that could change how he lived and her.

I do not believe her actions where justified

She had a lot going for her. She could have skipped the hardship of helping grace and pass. She could have easily have gotten a good job with a degree and paid back all the debts owed. Alot of troubles could have been avoided just by doing her own thing.

Answer:

6 kg

Explanation:

F=ma

F is Force(newtons)

m is mass(kg)

a is acceleration(m/s^2)

Plug in the numbers

3000 = m(500)

divide both sides by 500 to cancel out the 500.

3000/500=6

6 = m

6kg is the mass

Answer:

yes

Explanation:

becausw yesnssjsdkwww

Answer:

the average kinetic energy of the 10 molecules is 10 J.

Explanation:

Given;

energy on one molecule in motion, E = 100 J

number of molecules, n = 10

(A) The average kinetic energy of the 10 molecules

since the remaining 9 molecules are at rest, their kinetic energy = 0

[tex]E_{Avg} = \frac{E_1 + E_9}{10} \\\\E_{Avg} = \frac{100J+ 0}{10} \\\\E_{Avg} = \frac{100J}{10} \\\\E_{Avg} = 10J[/tex]

Therefore, the average kinetic energy of the 10 molecules is 10 J.

Answer:

Explanation:

Impulse = change in momentum

Initial momentum = mass x initial velocity = 100 x 5 = 500 kg m/s

final momentum = mass x final velocity = 100 x - 4 = -400 ( - ve sign due to reversal of direction )

change in momentum = final momentum - initial momentum

= - 400 - 500 = - 900 kg m/s .

As it is - ve , it acts upwards .

So magnitude of  impulse on Perter = 900 kg m/s

Answer:

Explanation:

Let n be number of total number of nucleons ( protons + neutrons )

Total mass inside nucleus =  n x 1.67 x 10⁻²⁷ Kg

volume of nucleus = 4/3 π r³

= 1.33 x 3.14 x (10⁻¹⁵)³ m

= 4.17 x 10⁻⁴⁵ m³

Density = mass / volume

=  n x 1.67 x 10⁻²⁷ / 4.17 x 10⁻⁴⁵

= .4 n x 10¹⁸ kg / m³

or of the order of 10¹⁸ kg/m³

b )

Density of iron = 7900 kg / m³

or of the order of 10⁴ kg / m³

So nucleus of a matter  is about 10¹⁴ times denser than iron .

Answer:

  λ = 440 nm

Explanation:

The phenomenon of constructive interference is described by the expressions

          d sin θ= m λ                    (1)

where d is the separation of the slits d = 0.0250 mm = 2.50 10⁻⁵ m, lam is the wavelength of the incident radiation and m is an integer indicating the order of interference

let's use trigonometry to find the angle

          tan θ = y / L

where L is the distance to the screen L = 1.25 m

in general interference experiments angles are very small

         tan θ = [tex]\frac{sin \ \theta }{cos \ \theta}[/tex]

         ten θ = sin θ

substituting

         sin θ = y / L

we substitute 1

          d y / L = m λ

          λ = [tex]\frac{ d \ y }{m \ L}[/tex]

in the exercise indicate

        m = 3

         y = 6.6 cm = 6.6 10-2 m

we calculate

          λ = 2.50 10⁻⁵ 6.6 10⁻² /( 3   1.25)

          λ = 4.4 10⁻⁷ m

let's reduce to nm

          λ = 4.4 10⁻⁷ m (10⁹ nm / 1 m)

          λ = 440 nm

Correct temperature is 80°F

Answer:

T_f = 38.83°F

Explanation:

We are given;

Volume; V = 8 ft³

Initial Pressure; P_i = 100 lbf/in² = 100 × 12² lbf/ft²

Initial temperature; T_i = 80°F = 539.67 °R

Time for outlet flow; t_o = 90 s

Mass flow rate at outlet; m'_o = 0.03 lb/s

Final pressure; P_f = 30 lbf/in² = 30 × 12² lbf/ft²

Now, from ideal gas equation,

Pv = RT

Where v is initial specific volume

R is ideal gas constant = 53.33 ft.lbf/°R

Thus;

v = RT/P

v_i = 53.33 × 539.67/(100 × 12²)

v_i = 2 ft³/lb

Formula for initial mass is;

m_i = V/v_i

m_i = 8/2

m_i = 4 lb

Now change in mass is given as;

Δm = m'_o × t_o

Δm = 0.03 × 90

Δm = 2.7 lb

Now,

m_f = m_i - Δm

Thus; m_f = 4 - 2.7

m_f = 1.3 lb

Similarly in above;

v_f = V/m_f

v_f = 8/1.3

v_f = 6.154 ft³/lb

Again;

Pv = RT

Thus;

T_f = P_f•v_f/R

T_f = (30 × 12² × 6.154)/53.33

T_f = 498.5°R

Converting to °F gives;

T_f = 38.83°F

The final temperature, in °F, of the air remaining in the tank is 38.83°F

It is given that volume V = 8 ft³

Initial Pressure Pi = 100 lbf/in² = 100 × 12² lbf/ft²

Initial temperature Ti = 80°F = 539.67 °R

Time for outlet flow; to = 90 s

Mass flow rate at outlet; m'o = 0.03 lb/s

Final pressure; Pf = 30 lbf/in² = 30 × 12² lbf/ft²

Now, from ideal gas equation,

Pv = RT

where v is initial volume, R is ideal gas constant = 53.33 ft.lbf/°R

[tex]v = RT/P\\ \\ v_i = 53.33 *539.67/(100*12^2)\\ \\ v_i = 2 ft^3/lb [/tex]

The initial mass is;

[tex]m_i = V/v_i\\ \\ m_i = 8/2\\ \\ m_i = 4 lb [/tex]

Now change in mass is given as;

Δm = [tex]m'_o*t_o[/tex]

Δm = 0.03 × 90

Δm = 2.7 lb

[tex]m_f[/tex] = [tex]m_i[/tex] - Δm

[tex]m_f[/tex] = 4 - 2.7

[tex]m_f[/tex] = 1.3 lb

now,

[tex]v_f = V/m_f\\ \\ v_f = 8/1.3\\ \\ v_f = 6.154 f^3/lb [/tex]

From the gas equation

Pv = RT

Final state:

[tex]T_f = P_fv_f/R\\\\ T_f = (30*12^2*6.154)/53.33\\\\ T_f = 498.5^oR [/tex]

Converting to °F:

[tex]T_f[/tex] = 38.83°F is the final temperature.

Learn More:

https://brainly.com/question/18518493

Answer:

30 m/s

Explanation:

Speed is distance over time. 60 meters / 2 seconds, = 30 m/s.

Answer:

4363.3231 feets²

Explanation:

Given that :

Distance, r = 50 ft

θ = 200°

The arc length of area covered :

Arc length = θ/360° * πr²

Arc length = (200/360) * 50 ft ^2 * π

Arc length = 0.5555555 * 2500 * π

Arc length = 4363.3231 feets²

Answer:

25 m/s

Explanation:

Given that:

Initial speed, u = 4 m/s

Final velocity, V = 11 m/s

Time, t = 8 seconds

t2, = 16 seconds

Acceleration, a= (change in velocity) / time interval

a = (11 - 4) / 8

a = 7 / 8 = 0.875m/s²

Final velocity, v2 ;

Acceleration * t2

0.875 * 16 = 14

V2 = 14 m/s

Final speed : v + v2 = (11 + 14)m/s = 25m/s

Answer:

E_total = 26.97 N/C

Electric field points towards the positive charge

Explanation:

We are given;

Charge 1; q1 = 6 nC = 6 × 10^(-9) C

Charge 2; q2 = 3 nC = 3 × 10^(-9) C

Distance between both charges; R_o = 2 m

Since we want to find electric field midway, the distance midway is r = 2/2 = 1 m

Using coulumbs law;

E = kq/r²

Where k is a constant with a value of 8.99 × 10^(9) N.m/C²

Thus;

E1 = kq1/r²

E1 = (8.99 × 10^(9) × 6 × 10^(-9))/1²

E1 = 53.94 N/C

Similarly;

E2 = kq2/r²

E2 = (8.99 × 10^(9) × 3 × 10^(-9))/1²

E2 = 26.97 N/C

Since both electric fields are positive, it means that they are both moving towards the midpoint of the distance between both charges.

This implies they will have opposite directions.

Thus, total electric field at the midway point is;

E_total = E1 - E2

E_total = 53.94 - 26.97

E_total = 26.97 N/C

Answer:

ITS B NOT A

Explanation:

Answer:

Vf = 21 m/s

Explanation:

Data:

Use formula:

Replace:

Multiply the acceleration with time:

Solve the sum:

The velocity of the car at the end of the 3 second interval is 21 meters per second.

Answer:

Semi-conservative

Explanation:

Each strand of the original DNA molecule serves as a template for the production of its counterpart

Answer:

the work done by friction on the car is 524,582 J.

Explanation:

Given;

mass of the roller coaster, m = 800 kg

distance moved by the coaster, d = 225 ft = 68.58 m

final velocity of the coaster, v = 80 mi/h = 35.76 m/s

The time taken for the coaster to drop down the hill is calculated as;

[tex]t = \sqrt{\frac{2h}{g} } \\\\t = \sqrt{\frac{2\ \times \ 68.58}{9.8} } \\\\t = 3.74 \ s[/tex]

The work done by friction on the car is calculated as;

[tex]W =F\ \times \ d = \frac{mv}{t} \times \ d\\\\W = \frac{800 \ \times \ 35.76 }{3.74} \times \ 68.58\\\\W = 524,582 \ J[/tex]

Therefore, the work done by friction on the car is 524,582 J.

Answer:

he two people agree with your answer

  v_B = v_{oB} - a t

              v_A = cte

Explanation:

To analyze if they are both in Kurdish, let's see the movement of the two cars

at t = 1s

the velocity of carriage B is greater than the speed of carriage a

             v_B> v_A

at t = 2 s

the speed of the two cars is nipple

              v_B = v_A

For this to be true, the speed of car B must be decreasing

              v_B = v_{oB} - a t

              v_A = cte

therefore the two people agree with your answer

Answer:

convection currents

Explanation:

Answer:

(A)

A cup placed on a table won't float away