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mash [69]
3 years ago
11

A car of the future requires 15kW of power to travel along a level road at 65km/h. A physics student wishes to use the car to dr

ive from Bowser to Qualicum, a distance of about 25 km. The engine is driven by heat energy recovered from a special material which has a specific heat capacity of 9800 J/kg • degree Celsius, If the car has 350 kg of this material, the outside air temperature is 15 °c and the engine is 88% efficient, to what temperature must the material be heated?
Physics
1 answer:
Luda [366]3 years ago
7 0
Power = Energy / time, The time is the one it takes to cover 25 km at 65 km/h, so:  time = 25/65*60*60 = 1384.6 seconds.

Now the total energy needed for that is: Energy = Power * time = 15,000 * 1384.6 = 20769239.8 J.

The heat provides those J. The heat for a difference in temperature is:

Heat = mass * c_h * Difference_of_temperature,

Heat = 350 * 9,800 * (T-15)*0.88,

where the 0.88 is because some of the heat is lost, efficiency 88%. Now, you can equal both results and get T:

350*9,800*0.88*(T-15) = 20769239.8

T-15 = 6.88, and T = 21.88 C

The answer is T= 21.88 C

NB: this specific heat, 9,800, is more than 2,000 time sthat of water, it is really a substance that does not exist,. It seems He has the highest (5,300) but it's a gas!
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3 years ago
What is the frequency of a wave that has a wavelength of 20 cm and a speed of 10 m/s
jarptica [38.1K]
You would probably have a low frequency due to how much the wavelength is spread out.
8 0
3 years ago
How Does Earth's gravitational force field act on objects that aren't touching Earth's surface?
natali 33 [55]

Answer:

Explanation:

Gravity is a field force since the earth does not have to actually “touch” an object to pull it toward the earth. A magnetic force is a field force that attracts or repels another magnet. Likewise, electric charges cause attracting or repelling forces without actual contact between the charges

8 0
2 years ago
One gallon of paint (volume = 3.79 X 10-???? m3) covers an area of 25.0 m2. What i the thickne s of the fresh paint on the wall?
Drupady [299]

Answer:

Explanation:

Given

Volume of paint is V=3.79\times 10^{-3}\ m^3

Area of cover A=25\ m^2

Suppose paint to be a rectangular box with thickness t and volume V

therefore we can write as

V=A\times t

t=\frac{V}{A}

t=\frac{3.79\times 10^{-3}}{25}

t=1.516\times 10^{-3}\ m

t=1.516\ mm  

6 0
3 years ago
A 0.950 kg block is attached to a spring with spring constant 16.0 N/m . While the block is sitting at rest, a student hits it w
Bumek [7]

Answer:

Explanation:

Given that,

Mass attached m = 0.95kg

Spring constant k = 16N/m

Instantaneous speed v = 36cm/s = 0.36m/s

Amplitude A=?

When x = 0.7A

Using conservation of energy

∆K.E + ∆P.E = 0

K.E(final) — K.E(initial) + P.E(final) — P.E(initial) = 0

At the beginning immediately the hammer hits the mass, the potential energy is 0J, Therefore, P.E(initial) = 0J, so the speed is maximum.

Also, at the end, at maximum displacement, the speed is zero, therefore, K.E(final) = 0

So, the equation becomes

— K.E(initial) + P.E(final) = 0

K.E(initial) = P.E(final)

½mv² = ½kA²

mv² = kA²

0.95 × 0.36² = 16×A²

0.12312 = 16•A²

A² = 0.12312/16

A² = 0.007695

A = √0.007695

A = 0.088 m

A = 8.8cm

B. Speed at x = 0.7A

Using the same principle above

K.E(initial) = P.E(final)

½mv² = ½kA²

Where A = 0.7A = 0.7 × 0.088 = 0.0614m

Then,

½× 0.95 × v² = ½ × 16 × 0.0614²

0.475v² = 0.0310644

v² = 0.0310644/0.475

v² = 0.0635

v = √0.0635

v = 0.252 m/s

v = 25.2 cm/s

8 0
3 years ago
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