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MrRa [10]
3 years ago
6

As a runner crosses the finish line of a race, she starts decelerating from a velocity of 9 m/s at a rate of 2 m/s^2. Take the r

unner's velocity as she crosses the finish line to be in the positive direction. What is the runner’s displacement, in meters, during the first 5 seconds after crossing the finish line?
What is her velocity, in meters per second, 5 seconds after crossing the finish line?
Physics
1 answer:
Ksivusya [100]3 years ago
4 0

Answer:

- 1 m/s, 20 m

Explanation:

u = 9 m/s, a = - 2 m/s^2, t = 5 sec

Let s be the displacement and v be the velocity after 5 seconds

Use first equation of motion.

v = u + a t

v = 9 - 2 x 5 = 9 - 10 = - 1 m/s

Use second equation of motion

s = u t + 1/2 a t^2

s = 9 x 5 - 1/2 x 2 x 5 x 5

s = 45 - 25 = 20 m

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Answer:

K.E = 120 Joules.

Explanation:

<u>Given the following data;</u>

Mass = 0.15kg

Distance = 1m

Velocity = 40m/s

To find kinetic energy;

Kinetic energy can be defined as an energy possessed by an object or body due to its motion.

Mathematically, kinetic energy is given by the formula;

K.E = \frac{1}{2}MV^{2}

Where;

  • K.E represents kinetic energy measured in Joules.
  • M represents mass measured in kilograms.
  • V represents velocity measured in metres per seconds square.

Substituting into the equation, we have;

K.E = \frac{1}{2}*0.15*40^{2}

K.E = 0.075*1600

<em>K.E = 120 Joules.</em>

<em>Therefore, the kinetic energy of the baseball is 120 Joules. </em>

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3 years ago
What Is the definition of the term gravitational potential energy​
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Answer:

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Explanation:

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Which form of energy does Theodore Roosevelt Lake have as the water collects in the
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A woman dropped a dime in a wishing well , she heard it 30 sec later ..Find velocity on impact while moving at 9.8 m/s 2
VMariaS [17]

Answer:

The velocity at impact is 222.2 m/s

Explanation:

The given information are;

The time at which the woman heard the sound of the coin after dropping it into the wishing well = 30 seconds

The average speed of sound in air = 344 m/s

The time in which the dime travel = t₁

The time in which the sound travel = t₂

1/2 × 9.8 × t₁² = 344 × t₂

t₁ + t₂ = 30

4.9·t₁² = 344 × (30 - t₁)

4.9·t₁² + 344·t₁ - 10320 = 0

Which gives -344±

t_1 = \dfrac{-344\pm \sqrt{344^{2}-4\times 4.9 \times 10320}}{2\times 4.9}

t₁  = 22.676 seconds or -92.9 seconds

Therefore the correct natural time is t₁  = 22.676 seconds

The velocity at impact, v = g×t₁ = 9.8 × 22.676  = 222.2 m/s

The velocity at impact= 222.2 m/s.

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