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vaieri [72.5K]
3 years ago
5

Could someone explain to me how to got the answer B, thank you very much​

Physics
1 answer:
Mnenie [13.5K]3 years ago
4 0

Answer:

since -6 lasted for 5 seconds, multiplying both would result in -30

3 lasted for 10 seconds, so multiplying both would give +30

average = ( 30 + (-30) ) / 2

30 -30 is already equal to zero, so the answer should be 0

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A 50 kg runner runs up a flight of stairs. The runner starts out covering 3 steps every second. At the end the runner stops. Thi
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To solve the problem it is necessary to take into account the concepts of kinematic equations of motion and the work done by a body.

In the case of work, we know that it is defined by,

W = F * d

Where,

F= Force

d = Distance

The distance in this case is a composition between number of steps and the height. Then,

d=h*N, for h as the height of each step and N number of steps.

On the other hand we have the speed changes, depending on the displacement and acceleration (omitting time)

V_f^2-V_i^2 = 2a\Delta X

Where,

V_f = Final velocity

V_i = Initial Velocity

a = Acceleration

\Delta X = Displacement

PART A) For the particular case of work we know then that,

W = F*d

W = m*g*(h*N)

W = 50*9.8*(0.3*30)

W = 4.41kJ

Therefore the Work to do that activity is 4.41kJ

PART B) To find the acceleration (from which we can later find the time) we start from the previously given equation,

V_f^2-V_i^2 = 2a\Delta X

Here,

V_i = \frac{0.3*3}{1} = 0.90m/s\rightarrow3 steps in one second

v_f = 0

Replacing,

V_f^2-V_i^2 = 2a\Delta X

0-0.9^2=2a(30*0.3)

Re-arrange for a,

a = -\frac{0.9^2}{2*30*0.3}

a = -45*10^{-3}m/s^2

At this point we can calculate the time, which is,

t = \frac{\Delta V}{a}

t = \frac{0-0.9}{-45*10^{-3}}

t = 20s

With time and work we can finally calculate the power

P = \frac{W}{t} = \frac{4.41}{20}

P = 0.2205kW

6 0
3 years ago
The ratio of output power to input power, in percent, is called
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That ratio is called"efficiency".  It doesn't need to be a percent. 
It can just as well be a fraction or a decimal number.

3 0
2 years ago
What is the conductor's resistance if its length is 2m and has a cross-sectional area of 0.7m with a resistivity of4Ωm? a. 1.4 Ω
Firlakuza [10]

Answer:

The answer is c. 11.42 Ohm

Explanation:

The conductor's resistance is calculated by the formula in the figure.

So, you have to replace the given values into the formula.

Resistance of a conductor is equal to the product of rho by the lengh of the conductor divided the cross-sectional area of the conductor.

R= 4 ohm.m . (2m/o.7m^{2} )\\R=11.42ohm

3 0
3 years ago
Your science teacher gives you three liquids to pour into a jar. After pouring, the liquids layer as seen here. What property of
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6 0
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A capacitor consists of two square plates, 8.7 cm on a side, separated by a 2.0 mm air gap. How much energy would be stored in t
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Answer:

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The distance between plates, d, is given in the question as 2mm=0.002m

Charge on plate, Q, as given in the question is 240 \mu c

Assuming mica dielectric constant, k of 7

Capacitance, C is given by

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5 0
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