A student weighing 5.4 × 102 newtons takes 15 seconds to run up a hill. The top of the hill is 10 meters vertically above her starting point. What power does the student develop during her run?

Answer:

 t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex],  v_r = 1 m/s       t ’= 547.19 s

Explanation:

This is a relative velocity exercise in a dimesion, since the river and the boat are going in the same direction.

By the time the boat goes up the river

        v_b - v_r = d / t

By the time the boat goes down the river

        v_b + v_r = d '/ t'

let's subtract the equations

       2 v_r = d ’/ t’ - d / t

       d ’/ t’ = 2v_r + d / t

       [tex]t' = \frac{d'}{ \frac{d}{t}+ 2 v_r }[/tex]

In the exercise they tell us

         d = 1.22 +1.45 = 2.67 km= 2.67 10³ m

         d ’= 1.45 km= 1.45 1.³ m

at time t = 69.1 min (60 s / 1min) = 4146 s

the speed of river is v_r

      t ’= [tex]\frac{1.45 \ 10^3}{ \frac{ 2670}{4146} \ + 2 \ v_r}[/tex]

      t ’= [tex]\frac{1450}{0.6499 + 2 v_r}[/tex]

In order to complete the calculation, we must assume a river speed

          v_r = 1 m / s

let's calculate

      t ’= [tex]\frac{ 1450}{ 0.6499 + 2 \ 1}[/tex]

      t ’= 547.19 s

Answer:

a) time taken to catch up with speeding car is 12.25 secs

b) the police car will travel 273.8 m to catch up with the speeding car

Explanation:

Given that;

speed of car [tex]V_{c}[/tex] = 50 mi/hr = 22.352 m/s

acceleration of police car = 10 mi/hr = 4.47 m/s²

[tex]V_{f}[/tex]  = 70 mi/hr = 31.29 m/s

Now time taken to reach maximum speed is t₁

so

[tex]V_{f}[/tex] =  [tex]V_{i}[/tex] + at₁

we substitute

31.29 = 0 + 4.47t₁

t₁ = 31.29 / 4.47

t₁  = 7 sec

now

d₁ = 0 + 1/2 × at₁²

d₁ = 0 + 1/2 × 0 + 4.47×(7)²

d₁ = 109.5 m

so distance travelled by the speeding car in time t₁  will be

[tex]d_{c}[/tex] = [tex]V_{c}[/tex] × t₁

we substitute

[tex]d_{c}[/tex] = 22.352 × 7

[tex]d_{c}[/tex]  = 156.46 m

now distance between polive car and speeding car

Δd =  [tex]d_{c}[/tex] - d₁

Δd = 156.46 - 109.5

Δd = 46.96 m

time taken to cover Δd will be

t₂ = Δd / ( [tex]V_{f}[/tex] - [tex]V_{c}[/tex] )

t₂ = 46.96 / ( 31.29 - 22.352 )

t₂ = 46.96 / 8.938

t₂ = 5.25 sec

distance travelled by the police in time t₂ will be

d₂ = [tex]V_{f}[/tex] × t₂

d₂ = 31.29 × 5.25

d₂ = 164.3 m

a) How long will it take before the officer catches up to the speeding car;

time taken to catch up with speeding car;

t = t₁ + t₂

t = 7 + 5.25

t = 12.25 secs

Therefore, time taken to catch up with speeding car is 12.25 secs

b)  how far will it have travelled in order to do so;

distance = d₁ + d₂

distance = 109.5 + 164.3

distance = 273.8 m

Therefore, the police car will travel 273.8 m to catch up with the speeding car

Answer:

Honestly, I don't know ¯\_(ツ)_/¯

Explanation:

Answer:

10s

Explanation:

Horizontal velocity is the velocity of an object in an horizontal direction

The ball's horizontal velocity is approximately 33.078 ft./s

Reason:

The known parameter are;

The horizontal distance the footballer kicks the ball, d = 43 yards

The time after which the ball lands, Δt = 3.9 seconds

Required:

To find the velocity of the ball

Solution:

[tex]Velocity = \dfrac{Distance}{Time} = \dfrac{d}{\Delta t}[/tex]

Therefore;

[tex]Horizontal \ velocity \ of \ the \ ball, \ v_x= \dfrac{43 \ yard}{3.9 \ seconds} \approx 11.026 \ yd/s[/tex]

The ball's horizontal velocity, vₓ ≈ 11.026 yd/s

1 yard = 3 feet

[tex]11.026 \ yard = 11.026 \ yard \times \dfrac{3 \ feet}{yard} = 22.078 \ feet[/tex]

The ball's horizontal velocity, vₓ ≈ 33.078 ft./s

Learn more about horizontal velocity here:

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Answer:

a) The final pressure is 1.68 atm.

b) The work done by the gas is 305.3 J.

Explanation:

a) The final pressure of an isothermal expansion is given by:

[tex] T = \frac{PV}{nR} [/tex]

[tex] T_{i} = T_{f} [/tex]

[tex] \frac{P_{i}V_{i}}{nR} = \frac{P_{f}V_{f}}{nR} [/tex]

Where:

[tex]P_{i}[/tex]: is the initial pressure = 5.79 atm

[tex]P_{f}[/tex]: is the final pressure =?

[tex]V_{i}[/tex]: is the initial volume = 420 cm³

[tex]V_{f}[/tex]: is the final volume = 1450 cm³

n: is the number of moles of the gas

R: is the gas constant

[tex] P_{f} = \frac{P_{i}V_{i}}{V_{f}} = \frac{5.79 atm*420 cm^{3}}{1450 cm^{3}} = 1.68 atm [/tex]

Hence, the final pressure is 1.68 atm.

b) The work done by the isothermal expansion is:

[tex] W = P_{i}V_{i}ln(\frac{V_{f}}{V_{i}}) = 5.79 atm*\frac{101325 Pa}{1 atm}*420 cm^{3}*\frac{1 m^{3}}{(100 cm)^{3}}ln(\frac{1450 cm^{3}}{420 cm^{3}}) = 305.3 J [/tex]

Therefore, the work done by the gas is 305.3 J.

I hope it helps you!        

Answer:

4=Conduction by convection by radiation.

Explanation:

Hope it will help you! It may be short but I don't know how to write it in blank aafai milayera lekha Hai blanks ma

Answer: reduced by 1/4

Explanation:

The force will be reduced by 1/4. Try plugging in 2r, then squaring it. You will get 4r^2, which is essentially dividing the force by 4

Answers:

8 kg

Explanation:

Kinetic Energy = (mass × velocity × velocity) ÷ 2

We know that Kinetic Energy = 400 J and velocity = 10 m/s.

KE = (m × v × v) ÷ 2

400 J = (m × 10 m/s × 10 m/s) ÷ 2

400 J = m × 50 m^2/s^2

To find the mass you will divide 400 J and 50 m^2/s^2.

m = 8 kg

You can also check it if it gives you 400 J.

KE = (m × v × v) ÷ 2

KE = (8 kg × 10 m/s × 10 m/s) ÷ 2

KE = 400 J

So this means that the mass is 8 kg. I know that it is a bit confusing, but when you do J (joules) ÷ m^2/s^2 = kg (kilograms). Hope this helps, thank you !!

Answer:

Stress, in physical sciences and engineering, force per unit area within materials that arises from externally applied forces, uneven heating, or permanent deformation and that permits an accurate description and prediction of elastic, plastic, and fluid behaviour.

I hope it's helpful!

Answer:

Option 10. 169.118 J/KgºC

Explanation:

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

Change in temperature (ΔT) = 20 °C

Heat (Q) absorbed = 1.61 KJ

Mass of metal bar = 476 g

Specific heat capacity (C) of metal bar =?

Next, we shall convert 1.61 KJ to joule (J). This can be obtained as follow:

1 kJ = 1000 J

Therefore,

1.61 KJ = 1.61 KJ × 1000 J / 1 kJ

1.61 KJ = 1610 J

Next, we shall convert 476 g to Kg. This can be obtained as follow:

1000 g = 1 Kg

Therefore,

476 g = 476 g × 1 Kg / 1000 g

476 g = 0.476 Kg

Finally, we shall determine the specific heat capacity of the metal bar. This can be obtained as follow:

Change in temperature (ΔT) = 20 °C

Heat (Q) absorbed = 1610 J

Mass of metal bar = 0.476 Kg

Specific heat capacity (C) of metal bar =?

Q = MCΔT

1610 = 0.476 × C × 20

1610 = 9.52 × C

Divide both side by 9.52

C = 1610 / 9.52

C = 169.118 J/KgºC

Thus, the specific heat capacity of the metal bar is 169.118 J/KgºC

Answer:

Force = 607.95 Newton

Explanation:

Given the following data;

Area = 0.00600 m^2

Pressure = 1 atm to Pascal = 101325 Pa

To find the force;

Pressure = Force/area

Force = pressure * area

Substituting into the equation, we have;

Force = 101325 * 0.00600

Force = 607.95 Newton.

Therefore, the amount of force exerted by the air on the stamp is 607.95 Newton.

Answer:

The south American plate

Answer:

T = 1.41 seconds

Explanation:

Given that,

The mass placed in the pendulum, m = 10 kg

The length of the pendulum, l = 0.5 m

We need to find the period of the pendulum. The relation for the period of the pendulum is given by :

[tex]T=2\pi \sqrt{\dfrac{l}{g}} \\\\T=2\pi \sqrt{\dfrac{0.5}{9.8}} \\\\T=1.41\ s[/tex]

So, the time period of the pendulum is 1.41 seconds.

For anyone that needs the correct answer without POS trolls:

The answer is 1.4 s

Thank me later :)

Answer:

The acceleration due to gravity at the location of the pendulum is 34.74 m/s².

Explanation:

Given that,

The length of a simple pendulum, l = 5.5 m

It makes 10.0 complete swings in 25 s.

Frequency of pendulum,

[tex]f=\dfrac{10}{25}\\\\f=0.4\ Hz[/tex]

The time period of a simple pendulum is given by :

[tex]T=2\pi \sqrt{\dfrac{l}{g}}[/tex]

Frequency,

[tex]f=\dfrac{1}{T}\\\\f=\dfrac{1}{2\pi \sqrt{\dfrac{l}{g}} }\\\\f=\dfrac{1}{2\pi}\sqrt{\dfrac{g}{l}}[/tex]

g is the acceleration due to gravity at the location where the pendulum is placed. So,

[tex]f^2=\dfrac{g}{4\pi^2l}\\\\g=f^2\times 4\pi^2l\\\\g=0.4^2\times 4\pi^2\times 5.5\\\\g=34.74\ m/s^2[/tex]

So, the acceleration due to gravity at the location of the pendulum is 34.74 m/s².

Answer:

an action-reaction pair is because one of the objects is often much more massive and appears to remain motionless when a force acts on it. It has so much inertia, or tendency to remain at rest, that it hardly

Answer: Waning Crescent

Explanation:

Answer:

Frank's 75% efficient light bulb will shine brighter.

Explanation:

The brightness of a bulb is gotten from the power equation;

P = I²R

The more the power rating in watts, the more the brightness.

Now, if they both use the same amount of energy but yet have different efficiency, it means we will just multiply the efficiency by the power.

Thus, 75% efficiency will yield more power than a 45% efficient one.

Therefore, Frank's light bulb will shine brighter.

Answer:

B. Light energy can exist independently of matter.

Explanation:

In science, matter can be defined as anything that has mass and occupies space. Any physical object that is found on earth is typically composed of matter. Matter are known to be made up of atoms and as a result has the property of existing in states.

Generally, matter exists in three (3) distinct or classical phases and these are;

I. Solid.

II. Liquid.

III. Gas.

Light energy is different from both sound and heat energy because light energy can exist independently of matter.

Generally, we know that light energy is a type of electromagnetic waves and as such do not require a medium of propagation for it to travel through a vacuum of space where no particles exist. For example, light energy from distant galaxy of stars and the sun.

However, both sound and heat energy are mechanical waves which are highly dependent on matter for their propagation and transmission.

Time needed = t = 20.83 s

Given

car speed = 85 km/h

truck speed = 73 km/h

Required

the time it takes for the car to reach the truck

Solution

When the car reaches the truck, the distance between them will be the same

x car - 250 m = x truck

General formula for distance (d) :

d = v.t

So the equation becomes :

85t-250 = 73t

12t=250

t = 20.83 s

Answer:

Ultraviolet rays from sun are very harmful from skin and can cause sunburn and skin diseases especially ultraviolet B rays. A sunscreen  lotion act as a protection barrier on the skin that restrict the direct contact of UV rays with skin and filter the harmful rays to enter the skin.

Radiotherapy is a medical therapy use to treat cancer. Radiotherapy commonly uses x-rays and gamma rays because they are high-energy particles or waves that kills or destroys the cancer cells.

Sunscreen lotion is able to filter this damaging ultraviolet radiation and prevent it from damaging the skin.

The sun reaches us from outer space brings ultraviolet rays to us. Ultraviolet rays are known to have some damaging effects on the skin. One way to protect our skin from this damaging ultraviolet rays is to use sunscreen lotion which is able to filter this damaging ultraviolet radiation and prevent it from damaging the skin.

X-rays and gamma rays are used in radiotherapy because they are light energy rays which are able to penetrate and destroy malignant cells in the body.

Learn more: https://brainly.com/question/13695751

Answer:

1.a) 3.93 m/s

 b) 0.80 s

2. a) 8.49 m

   b) 0.39 s

Explanation:

1. a) The speed at which the fox leaves the snow can be found as follows:

[tex] v_{f}^{2} = v_{0}^{2} - 2gH [/tex]

Where:

g: is the gravity = 9.80 m/s²

[tex]v_{f}[/tex]: is the final speed = 0 (at the maximum height)

[tex]v_{0}[/tex]: is the initial speed =?

H: is the maximum height = 79 cm = 0.79 m

[tex] v_{0} = \sqrt{2gH} = \sqrt{2*9.80 m/s^{2}*0.79 m} = 3.93 m/s [/tex]

Hence, the speed at which the fox leaves the snow is 3.93 m/s.

b) The time at which the fox reaches the maximum height is given by:

[tex]v_{f} = v_{0} - gt[/tex]

[tex]t = \frac{v_{0} - v_{f}}{g} = \frac{3.93 m/s}{9.80 m/s^{2}} = 0.40 s[/tex]

Now, the time of flight is:  

[tex] t_{v} = 2t = 2*0.40 s = 0.80 s [/tex]

2. a) The maximum height the ball reaches is:

[tex] H = \frac{v_{0}^{2} - v_{f}^{2}}{2g} = \frac{(12.9 m/s)^{2}}{2*9.80 m/s^{2}} = 8.49 m [/tex]

Then, the maximum height is 8.49 m.

b) The time at which the ball passes through half the maximum height is:

[tex]y_{f} = y_{0} + v_{0}t - \frac{1}{2}gt^{2}[/tex]

Taking y₀ = 0 and [tex]y_{f}[/tex] = 8.49/2 = 4.245 m we have:

[tex] 4.245 m -12.9m/s*t + \frac{1}{2}*9.80m/s^{2}*t^{2} = 0 [/tex]  

By solving the above quadratic equation we have:

t = 0.39 s

Therefore, the time at which the ball passes through half the maximum height when the ball is going up is 0.39 s.

I hope it helps you!                                                                                                      

Answer:

Explanation:

Considering non - relativistic approach : ----

Speed of electron = 1 % of speed of light

= .01 x 3 x 10⁸ m /s

= 3 x 10⁶ m /s

Kinetic energy of electron = 1/2 m v²

= .5 x 9.1 x 10⁻³¹ x ( 3 x 10⁶ )²

= 40.95 x 10⁻¹⁹ J

Kinetic energy in electron comes from lose of electrical energy equal to

Ve where V is potential difference under which electron is accelerated and e is electronic charge .

V x e = kinetic energy of electron

V x 1.6 x 10⁻¹⁹ = 40.95 x 10⁻¹⁹

V = 25.6 Volt .

Solution :

Length of the plastic rod , L = 1.6 m

Total charge on the plastic rod , Q = [tex]$-9 \times 10^{-8}$[/tex] C

The rod is divided into 8 pieces.

a). The length of the 8 pieces is , [tex]$l=\frac{L}{8}$[/tex]

                                                         [tex]$=\frac{1.6}{8}$[/tex]

                                                         = 0.2 m

b). Location of the center of the piece number 5 is given as : 0 m, -0.09375 m, 0 m.

c). The charge q on the piece number 5 is given as

[tex]$q=\frac{Q}{L}\times l$[/tex]

[tex]$q=\frac{-9 \times 10^{-8}}{1.6}\times0.2$[/tex]

 = [tex]$-1.125 \times 10^{-8}$[/tex] C

d). WE approximate that piece 5 as a point charge and we need to find out the field at point A(0.7 m, 0, 0) only due to the charge.

We know,  the Coulombs force constant, k = [tex]$8.99 \times 10^9 \ N.m^2/C^2$[/tex]

So the X component of the electric field at the point A  is given as

[tex]$E_x = 8.99 \times 10^9 \times 1 \times 10^{-8} \ \cos \frac{187.628}{0.70625}$[/tex]

     = -126.15 N/C

The Y component of the electric field at the point A is

[tex]$E_y = 8.99 \times 10^9 \times 1 \times 10^{-8} \ \sin \frac{187.628}{0.70625}$[/tex]

    = -16.93 N/C

Now since the rod and the point A is in the x - y plane, the z component of the field at point A due to the piece 5 will be zero.

∴ [tex]$E_z=0$[/tex]

Thus, [tex]$E= <-126.15,-16.93,0>$[/tex]

Answer:

Please see below as the answer is self-explanatory.

Explanation:

Answer:

Explanation:

a ) from San Antonio to Houston let distance be d km .

Average speed = total distance / total time

time = distance / speed

Total time = (d / 2 x 75 ) +( d / 2 x 106 )

= .0067 d + .0047 d

= .0114 d

Average speed  = d / .0114 d = 87.72 km /h

b ) from Houston back to San Antonio

Total time = (d / 2 x 106 ) +( d / 2 x 75 )

= .0047 d + .0067 d

= .0114 d

Average speed  = d / .0114 d = 87.72 km /h

c )

For entire trip :

total distance = 2d

total time = 2 x .0114 d

Average speed  = 2 d / 2 x .0114 d

= 87.72 km /h .