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tresset_1 [31]
2 years ago
13

A 55 kg track and field athlete has an average power output of 5.4 kW during the 200 meter dash. How quickly did she finish the

race?
Group of answer choices

a. 20 s

b. 22 s

c. 23 s

d. 18 s
Physics
1 answer:
olga_2 [115]2 years ago
5 0

The time taken for the athlete to finish the race is 20 s (Option A)

<h3>What is power? </h3>

Power is simply defined as the rate at which work is done. It can be expressed mathematically as

Power (P) = work (W) / time (t)

But

Work = weight × distance

Therefore,

Power = (weight × distance ) / time

<h3>How to determine the time </h3>
  • Mass (m) = 55 Kg
  • Acceleration due to gravity (g) = 9.8 m/s²
  • Weight = mg = 55 × 9.8 = 539 N
  • Power (P) = 5.4 KW = 5.4 × 1000 = 5400 W
  • Distance (d) = 200 m
  • Time (t) =?

Power = (weight × distance ) / time

5400 = (539 × 200) / t

5400 = 107800 / t

Cross multiply

5400 × t = 107800

Divide both side by 5400

t = 107800 / 5400

t = 20 s

Learn more about power:

brainly.com/question/5684937

#SPJ1

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satela [25.4K]

Answer:

a) t1 = v0/a0

b) t2 = v0/a0

c) v0^2/a0

Explanation:

A)

How much time does it take for the car to come to a full stop? Express your answer in terms of v0 and a0

Vf = 0

Vf = v0 - a0*t

0 = v0 - a0*t

a0*t = v0

t1 = v0/a0

B)

How much time does it take for the car to accelerate from the full stop to its original cruising speed? Express your answer in terms of v0 and a0.

at this point

U = 0

v0 = u + a0*t

v0 = 0 + a0*t

v0 = a0*t

t2 = v0/a0

C)

The train does not stop at the stoplight. How far behind the train is the car when the car reaches its original speed v0 again? Express the separation distance in terms of v0 and a0 . Your answer should be positive.

t1 = t2 = t

Distance covered by the train = v0 (2t) = 2v0t

and we know t = v0/a0

so distanced covered = 2v0 (v0/a0) = (2v0^2)/a0

now distance covered by car before coming to full stop

Vf2 = v0^2- 2a0s1

2a0s1 = v0^2

s1 = v0^2 / 2a0

After the full stop;

V0^2 = 2a0s2

s2 = v0^2/2a0

Snet = 2v0^2 /2a0 = v0^2/a0

Now the separation between train and car

= (2v0^2)/a0 - v0^2/a0

= v0^2/a0

8 0
4 years ago
Why do you think that if you drop two balls, exactly two balls rise on the other side at a similar speed? Why doesn’t one ball f
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It conserves both energy and momentum in the collision at the same time. By design, when the balls collide the strings that hold them up are vertical (assuming balls are only swung from one side).

: Hope this helps :)
7 0
3 years ago
In Part l, the independent variable was
Ber [7]

Answer:

The independent variable is the variable the experimenter manipulates or changes, and is assumed to have a direct effect on the dependent variable. ... The dependent variable is the variable being tested and measured in an experiment, and is 'dependent' on the independent variable.

7 0
3 years ago
PLEASE PLEASE HELP ME
SVEN [57.7K]

Microwaves are one of the lowest energies on the electromagnetic spectrum. While X-Rays are one of the highest energies on the electromagnetic spectrum. One similarity is that they are both on the electromagnetic spectrum. Also they both travel at the spped of light in a vacuum. One way they are different is They have different frequencies and wavelengths. Also they are used for different studies.

8 0
3 years ago
Calculate the change in internal energy of the following system: A balloon is cooled by removing 0.659 kJ of heat. It shrinks on
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<h2>Answer:</h2>

-310J

<h2>Explanation:</h2>

The change in internal energy (ΔE) of a system is the sum of the heat (Q) and work (W) done on or by the system. i.e

ΔE = Q + W       ----------------------(i)

If heat is released by the system, Q is negative. Else it is positive.

If work is done on the system, W is positive. Else it is negative.

<em>In this case, the system is the balloon and;</em>

Q = -0.659kJ = -695J    [Q is negative because heat is removed from the system(balloon)]

W = +385J  [W is positive because work is done on the system (balloon)]

<em>Substitute these values into equation (i) as follows;</em>

ΔE = -695 + 385

ΔE = -310J

Therefore, the change in internal energy is -310J

<em>PS: The negative value indicates that the system(balloon) has lost energy to its surrounding, thereby making the process exothermic.</em>

<em />

<em />

5 0
3 years ago
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