NUUS

A car starts from rest with an acceleration of 2.84 m/s2 at the instant when a second car moving with a velocity of 25.7 m/s pas

vredina [299]

Answer:

464.69 m

Explanation:

First car

$s=ut+\frac{1}{2}at^2\\\Rightarrow s=0\times t+\frac{1}{2}2.84t^2\\\Rightarrow s=1.42t^2$

Second car

Distance = Speed × Time

$\text{Distance}=25.7t$

Here, the time taken and the distance traveled will be the same

Equating the two equations

$1.42t^2=25.7t\\\Rightarrow t=\frac{25.7}{1.42}\\\Rightarrow t=18.09\ s$

So, the first would have to move $1.42t^2=1.42\times 18.09^2=464.69\ m$ in order to overtake the second car.

7 0

4 years ago

What would happen if a person who is wearing a heavy winter jacket were to place a thermometer inside the jacket next to his or

Scilla [17]

Answer:

Explained.

Explanation:

Let me explain the two cases in by one.

(1) When Person wearing a jacket, heat from his or her body is going to get trapped inside his or her jacket to keep this person warm when a thermometer is placed inside, it would indicate a higher temperature on the scale.

(2) When Jacket is Hanging in a closet, its temperature would be roughly close to room temperature and when we would place a thermometer it would not indicate any change on its scale.

7 0

3 years ago

when heated the temperature of a water sample increased from 15°C to 39°C. Is absorbed 41840 joules of heat. what is the mass of

Hunter-Best [27]

Answer:

Mass of water: 43 g

Explanation

hope it helps

6 0

3 years ago

A wind turbine is rotating at 15 rpm under steady winds flowing through the turbine at a rate of 42,000 kg/s. The tip velocity o

zzz [600]

Answer:

a) 5.22 m/s

b) 31.4 %

Explanation:

f = rotating speed = 15 rpm = 15/60 =0.25 rps

m = Mass flow rate of air = 42000 kg/s

v = Tip velocity = 250 km/h = 250/3.6 = 69.44 m/s

W = Work output = 180 kW

A = Swept area of wind turbine

r = Radius of wind turbine

η = Efficiency

$r=\frac{v}{2\pi f}\\\Rightarrow r=\frac{250\div 3.6}{2\pi 0.25}=\frac{250}{1.8\pi}$

$A=\pi r^2\\\Rightarrow A=\pi\left(\frac{250}{1.8\pi}\right)^2\\\Rightarrow A=\left(\frac{250}{1.8}\right)^2\frac{1}{\pi}$

$m=\rho V\\\Rightarrow m=\rho vA\\\Rightarrow v=\frac{m}{\rho A}\\\Rightarrow v=\frac{42000}{1.31 \left(\frac{250}{1.8}\right)^2\frac{1}{\pi}}\\\Rightarrow v=5.22\ m/s$

∴ The average velocity of the air is 5.22 m/s

$E=m\frac{v^2}{2}=42000\frac{5.22^2}{2}\\\Rightarrow E=572538.92$

$\eta=\frac{W}{E}=\frac{180000}{572538.92}\\\Rightarrow \eta =0.314$

∴ Conversion efficiency of the turbine is 0.314 or 31.4 %

7 0

3 years ago

Read 2 more answers

A transformer connected to a 110–(V) (rms) ac line is to supply 10.0 (V) (rms) to a portable electronic device. The load resista

spayn [35]

Answer:

Explanation:

a ) V( primary ) = 100 V

V( secondary ) = 10 V

No of turns ( secondary ) / No of turns ( primary ) = 10 / 100

= 1 / 10

b ) current in secondary

= volt ( secondary ) / resistance

= 10 /6 = 1.67 A

c )

Average power to secondary

= V ( secondary ) x current ( secondary )

= 10 x 10 / 6

= 16.67 W

d )

Power in primary = power in secondary = 16.67 W

e ) current drawn by ac line ( primary )

Volt ( primary ) x current ( primary ) = power in primary

= 16.67

current ( primary )

= 16.67 / 100

= 0.167 A

5 0

3 years ago