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Stels [109]
2 years ago
12

jeremie ran around the track at the ymca for 2 hours. when he was done he figured that he had traveled 20 kilometers. what was h

is speed? what was his velocity
Physics
1 answer:
laila [671]2 years ago
3 0
(1) Speed is the ratio of the total distance covered by the object and the total time it takes for him to finish it. 

    Speed = distance / time 

In this item, we are given that the distance is 20 kilometers and that the time it takes for the trip is 2 hours. Substituting the known values,
   Speed = 20 kilometers / 2 hours 
    speed = 20 km/h

(2) Velocity on the other hand takes into account the displacement of the object from his original position. It is assumed that Jeremie was basically back to his original position after two hours. Hence, the velocity is equal to zero. 
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A vertical spring has a spring constant of 2900 N/m. The spring is compressed 80 cm and a 8 kg spider is placed on the spring. T
Serga [27]

Answer:

a)  k_{e} = 928 J , b)U = -62.7 J , c) K = 0 , d) Y = 11.0367 m,  e)  v = 15.23 m / s  

Explanation:

To solve this exercise we will use the concepts of mechanical energy.

a) The elastic potential energy is

      k_{e} = ½ k x²

      k_{e} = ½ 2900 0.80²

      k_{e} = 928 J

b) place the origin at the point of the uncompressed spring, the spider's potential energy

     U = m h and

     U = 8 9.8 (-0.80)

     U = -62.7 J

c) Before releasing the spring the spider is still, so its true speed and therefore the kinetic energy also

      K = ½ m v²

      K = 0

d) write the energy at two points, maximum compression and maximum height

     Em₀ = ke = ½ m x²

     E_{mf} = mg y

     Emo = E_{mf}

     ½ k x² = m g y

     y = ½ k x² / m g

     y = ½ 2900 0.8² / (8 9.8)

     y = 11.8367 m

As zero was placed for the spring without stretching the height from that reference is

     Y = y- 0.80

     Y = 11.8367 -0.80

     Y = 11.0367 m

Bonus

Energy for maximum compression and uncompressed spring

     Emo = ½ k x² = 928 J

     E_{mf}= ½ m v²

     Emo = E_{mf}

     Emo = ½ m v²

      v =√ 2Emo / m

     v = √ (2 928/8)

     v = 15.23 m / s

8 0
3 years ago
The speed of an object and the direction in which it moves constitute a vector quantity known as the velocity. an ostrich is run
Orlov [11]
Velocity of an object is its rate of change of the object's position per interval of time. Velocity is a vector quantity which means that it consists of a magnitude and a direction. Magnitude is represented by the speed and the direction is represented by the angle. To determine the velocity components, we use trigonometric functions to determine the angle of the components. For the north component we, use the sine function while, for the west component, we use the cosine function. We calculate as follows:
north velocity component = (16.8 m/s) (sin 54°) = 16.4 m/s
<span>west velocity component = (16.8 m/s) (cos 54°) = 3.49 m/s</span>



6 0
3 years ago
Why are many mitochondria needed in cells that move, like muscle cells?
Deffense [45]
Muscle cells have to use a lot of energy and the Mitochondria is known as the "power house" of the cell... I would say the number of mitochondria needed is increased because more power and energy is being used in that cell than a normal one (idk if this helps or if that's the answer you were looking for)
3 0
2 years ago
A steel pot has a bottom with a cross sectional area of .1m2 and has a thickness of 1cm. The pot is filled with boiling water an
jenyasd209 [6]

Answer:

840000 J/min

Explanation:

Area = A = 0.1 m²

Bottom of pot temperature = 200 °C

Thermal conductivity = k = 14 J/sm°C

Thickness = L = 1 cm = 0.01 m

Temperature of boiling water = 100 °C

From the law of heat conduction

Q = kAΔT/L

⇒ Q = 14×0.1×(200-100)/0.01

⇒ Q = 14000 J/s

Converting to J/minute

Q = 14000×60 = 840000 J/min

∴ Heat being conducted through the pot is 840000 J/min

3 0
3 years ago
The morning of a birthday party, a balloon is filled with 8.5 L of helium (He) when the temperature is 294 kelvin. The party sta
Phoenix [80]

Explanation:

the morning of the birthday party balloon filled with the 2.5 Litre of helium

temperature is 294kelvin

the party starts at the 4 p.m.

temperature rises 305 Kelvin.

the new volume = 4 litre.

At same temperature,

P

1

V

2

=P

2

V

2

(Boyle's law)

P

1

=10atm;P

2

=1atm

V

1

=4l=V

2

=8l

But while filling balloons from cylinder when pressure in cylinder becomes 1 atm then further filling is not possible (P

1

′

=9atm)

Let n be the number of balloons that can be filled.

∴P

1

′

V

1

=n(P

1

V

1

)

9×8=n(4×1)

n=

4

9×8

=18balloons

5 0
2 years ago
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