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2 years ago

A car is driving on the road. The car starts to decelerate at -3 m/s2. It stops moving after 125

Physics

1 answer:

galina1969 [7]2 years ago

8 0

Answer:

27.39 m/s

Explanation:

From the question given above, the following data were obtained:

Deceleration (a) = –3 m/s²

Distance (s) = 125 m

Final velocity (v) = 0 m/s

Initial velocity (u) =?

The initial velocity (u) of the car can be obtained as follow:

v² = u² + 2as

0² = u² + (2 × –3 × 125)

0 = u² + (– 750)

0 = u² – 750

Collect like terms

0 + 750 = u²

750 = u²

Take the square root of both side

u = √750

u = 27.39 m/s

Thus, the initial velocity of the car was 27.39 m/s

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2 years ago

A motorcyclist drove 7 km at 57km/h and then another 7 km at 81 km/h. What was the average speed?

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Answer:

The average speed of the car is 66.9 km/h

Explanation:

Here distance covered with the speed 57 km/h=7 km 

distance covered with the speed of 81 km/h=7 km

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Shortcut: 

When equal distances are covered with different speeds average speed=2 ab/(a+b) where a and b are the variable speeds in the phases. 

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2 years ago

liquid helium has a very low boiling point, 4.2 k, as well as a very low latent heat of vaporization, 2.00 104 j/kg. if energy i

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$4.80 \times 10^3 \text { seconds }$ long does it take to boil away 2.40 kg of the liquid.

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Power of electrical heater $P=30 \mathrm{w}$

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amount of heat required to boil

$\begin{aligned}&Q=m L \\&Q=2.40 \times 2 \times 10^4 \mathrm{~J} \\&Q=4.80 \times 10^4 \mathrm{~J}\end{aligned}$

Power $p=\frac{\text { work }}{\text { time }}=\frac{\text { Energy }}{\text { Time }}$

$\begin{aligned}P &=\frac{Q}{t} \\\text { tine } t &=\frac{Q}{P}=\frac{4.80 \times 10^4 \mathrm{~J}}{10} \\t &=4.80 \times 10^3 \text { seconds }\end{aligned}$

The heat or energy that is absorbed or released during a substance's phase shift is known as latent heat. It could go from a solid to a liquid or from a liquid to a gas, or vice versa. Enthalpy, a characteristic of heat, is connected to latent heat.

The heat that is used or lost as matter melts and transitions from a solid to a fluid form at a constant temperature is known as the latent heat of fusion.

Due to the fact that during softening the heat energy anticipated to transform the substance from solid to fluid at air pressure is the latent heat of fusion and that the temperature remains constant during the process, the "enthalpy" of fusion is a latent heat. The enthalpy change of any quantity of material during dissolution is known as the latent heat of fusion.

For learn more about Latent heat of vaporization, visit: brainly.com/question/14980744

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