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Papessa [141]
2 years ago
8

After the first few seconds of a race, a runner runs at the same speed until she approaches the finish line, at which point she

increases her speed. Which statement best explains why she only did work at the beginning and end of the race? (Ignore work done against air resistance and friction.)
Physics
1 answer:
Rzqust [24]2 years ago
5 0

DUJFIOflmC VANWSER

EXPLANTATION

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Under the influence of its drive force, a snowmobile is moving at a constant velocity along a horizontal patch of snow. When the
balandron [24]

Answer:

a) Δx = 11.6 m

b) t = 3.9 s

Explanation:

a)

  • Since the snowmobile is moving at constant speed, and the drive force is 195 N, this means that thereis another force equal and opposite acting on it, according to Newton's 2nd Law, due to there is no acceleration present in the horizontal direction .
  • This force is just the force of kinetic friction, and is equal to -195 N (assuming the positive direction as the direction of the movement).
  • Once the drive force is shut off, the only force acting on the snowmobile remains the friction force.
  • According Newton's 2nd Law, this force is causing a negative acceleration (actually slowing down the snowmobile) that can be found as follows:

       a = \frac{F_{fr} }{m} = \frac{-195N}{128kg} = -1.5 m/s2 (1)

  • Assuming the friction force keeps constant, we can use the following kinematic equation in order to find the distance traveled under this acceleration before coming to an stop, as follows:

       v_{f} ^{2}  -v_{o} ^{2} = 2* a* \Delta x (2)

  • Taking into account that vf=0, replacing by the given (v₀) and a from (1), we can solve for Δx, as follows:

       \Delta x =- \frac{v_{o}^{2}}{2*a} =- \frac{(5.90m/s)^{2}}{2*(-1.5m/s2)} = 11.6 m (3)

b)

  • We can find the time needed to come to an stop, applying the definition of acceleration, as follows:

       v_{f} = v_{o} + a*\Delta t (4)

  • Since we have already said that the snowmobile comes to an stop, this means that vf = 0.
  • Replacing a and v₀ as we did in (3), we can solve for Δt as follows:

       \Delta t = \frac{-v_{o} }{a} = \frac{-5.9m/s}{-1.5m/s2} = 3.9 s   (5)

7 0
2 years ago
The Force of friction between an object and the surface upon which it is sliding is 12N. The weight of the object is 20N. What i
VashaNatasha [74]

Answer:

Explanation:

Reducing Sliding Friction. You can reduce the resistive force of sliding friction by applying lubrication between the two surfaces in contact, by using rollers, or by decreasing the normal force

6 0
3 years ago
according to newtons second law of motion, when an object is acted on by an unbalanced force, how will that object respond?
olga_2 [115]
When an object is acted on by an unbalanced force, then that object will accelerate.
6 0
2 years ago
Read 2 more answers
The distance between earth and sun is 15000000km. Light takes 499 seconds to reach earth from sun. Calculate the speed of light
iVinArrow [24]

To solve the problem we must know about the relationship between Speed, distance, and Time.

<h3>What is the relationship between Speed, distance, and Time?</h3>

We know that sped, distance, and time all are in a relationship to each other. this relationship can be given as,

\rm{Speed = \dfrac{Distance}{Time}

The speed of the light is 30,060.12 km/sec.

Given to us

  • The distance between the earth and the sun is 15000000km
  • Light takes 499 seconds to reach earth from the sun.

We know that speed can be described as,

\rm{Speed = \dfrac{Distance}{Time}

Therefore,

<h3>What is the speed of the light?</h3>

\text{Speed of light} = \dfrac{\text{Distance between the earth and the sun}}{\text{Time taken by the light to travel the distance}}

Substitute the value,

\text{Speed of light} = \dfrac{15,000,000\ km}{499\ seconds}

\text{Speed of light} = 30,060.12\ km/sec

Hence, the speed of the light is  30,060.12 km/sec.

Learn more about Speed, distance, and Time:

brainly.com/question/15100898

7 0
2 years ago
Read 2 more answers
On the way to school, Jed traveled 100m north, 300m east, 100 north, 100m east, and 100m north. A.) Find the total distance trav
Oduvanchick [21]

Answer:

Total distance = 700 m

Displacement = 500 m

Explanation:

Notice that Jed travelled a total of 3 x 100 m = 300 m in the North direction, and 300 m + 100 m = 400 m in the East direction. Therefore the total distance he travelled is:  300 + 400 = 700 m.

But the actual displacement is given by the Pythagorean theorem as the hypotenuse of a right angle triangle of legs 300 m and 400 m:

displacement = \sqrt{300^2+400^2} =\sqrt{250000} =500\,m

5 0
3 years ago
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