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3 years ago

A runner with a mass of 80kg accelerates from 0 to 9 m/s in 3 s find the net force

1 answer:

4 0

So, first you find your acceleration which is 3m/s^2, using the acceleration formula.
Now set up your equation, F=ma, so put in the stuff, F=80kg·3m/s^2. Then solve your equation by multiplying, and you get F=240N, since newtons are your measurement.
Hope this helps

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A 500 W hair dyer is used to dry hair for 6 minutes a day for 3 days. How much energy is used? A laptop uses 75 W. The cot of el

zzz [600]

Answer:

See the answers below.

Explanation:

We will solve this problem by calculating each part separately.

A 500 W hair dyer is used to dry hair for 6 minutes a day for 3 days.

Energy can be calculated by multiplying the value of the power of the equipment by the amount of time of use.

$500 [W]*[\frac{6min}{1day} ]*[\frac{1day}{24hr} ]*[\frac{1hr}{60min} ]=2.083 [W]$

The cots of electricity is 5.6 cents per kWh. How much would it cost to operate the laptop for 24 hours a day for one week?

We know that the power of the latop is 75 [W], then we can calculate the cost, multiplying the value of the power by the value of the cost by the time of use of the computer.

$0.075[kW]*5.6[\frac{cents}{kw*h}}]*[\frac{24hr}{1day}]*[1week]*[\frac{7days}{1week} ]=70.56 [cents]$

A toaster oven is 85% efficient. It uses 1200 J of energy. How much thermal energy is it producing?

Efficiency is defined as the relationship between the energy obtained on the energy delivered. Almost always the energy delivered is greater than the energy obtained (first law of thermodynamics).

Therefore.

$Effic = E_{obtained}/E_{delivered}\\0.85=E_{obtained}/1200\\E_{obtained}=1020[J]$

4 0

2 years ago

Thomson is responsible for discovering that an atom containing _________

EastWind [94]

protons, neutrons, and electrons.

6 0

3 years ago

Read 2 more answers

Why does a gymnast rub powder on his hands before exercising on a set of parallel bars? (I need a scientific answer)

dlinn [17]

Answer

To increase friction for a better grip.

Answer

Most human beings do sweat hands especially on the palm. When this happens the person will not have a good grip of heavy objects because they will slide/slip from the hand.

By applying the powder, you are trying to make the hand dry hence increasing the friction for a better grip.

If the gymnast doesn't do this the parallel bars may slip from the hands and injure himself or herself.

4 0

2 years ago

Read 2 more answers

imagine that 501 people are present in a movie theater of volume 8.00 x10^3 that is sealed shut so no air can escape. Each perso

Semenov [28]

Answer:

The temperature of air will increase by $\Delta T=41044.967\ K$

Explanation:

Given:

no. of person in a theater, $n=501$

volume of air in the theater, $V=8\times 10^3\ m^3$

rate of heat given off by each person, $P=110\ J.s^{-1}$

duration of movie, $t=2\ hr=7200\ s$

initial pressure in the theater, $p_i=1.01\times 10^5\ Pa$

initial temperature in the theater, $T_i=20+273=293\ K$

specific heat capacity of air at the given conditions, $c=1.0061\ J.kg^{-1}.K^{-1}$

The total quantity of heat released by the total people in the theater during the movie:

$Q=n.P.t$

$Q=501\times 110\times 7200$

$Q=396792000\ J$

Form the relation of heat capacity:

$Q=m.c.\Delta T$

∵ $p_i.V=m.R.T$

$Q=(\frac{p_i.V}{R.T}) \times c\times (T_f-T_i)$

$396792000=(\frac{1.01\times 10^5\times 8\times 10^3}{287\times 293}) \times 1.0061\times (T_f-293)$

$T_f=41337.967\ K$

Change in temperature of air:

$\Delta T=41044.967\ K$

8 0

2 years ago

Which of the following is an example of a safe laboratory produced?

Step2247 [10]

I think you meant to say "procedure" instead of "produced".

Choice B is the answer as it is the safest and most sensible (to prevent damage to clothing or start a fire for example). The other choices are nonsensical or silly.

8 0

3 years ago