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3 years ago

A car drives 10km with a speed of 72 km/hr and then runs out of gas. Then you walk 2km for the next 30 min

Physics

1 answer:

marin [14]3 years ago

5 0

Given :

A car drives 10 km with a speed of 72 km/hr and then runs out of gas.

Then you walk 2 km for the next 30 min until you find a gas station .

To Find :

The average speed of whole journey .

Solution :

Average speed is given by :

$v_{avg}=\dfrac{\text{Total distance covered}}{\text{Total time taken}}\\\\v_{avg}=\dfrac{10+2}{\dfrac{10}{72}+\dfrac{1}{2}}\\\\\\v_{avg}=18.78\ km/hr$

Hence , this is the required solution .

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What conclusions can you draw about the connection between the Sun’s altitude and the latitude of the observer on seasonal chang

Cerrena [4.2K]

Answer:

Explanation:

Altitude of the Sun and the latitude position on the earth play an important role in the season change on the earth.

When the altitude of the sun is high then the average temperature of the earth is higher because the luminous intensity of the sun rays is higher due to the focusing of high energy sun rays over a small area.

But when the sun is at higher altitudes we receive less denser rays of the sun and hence we have less heat on the earth on an average.

But despite of the altitude some places on the earth have distinct temperature than the other place at the same time of the year. This is due to their latitudinal location. The places near the equator are warmer most of the times throughout the year because they receive the most direct rays while the poles receive slanting rays and hence are colder even in summer when the earth is at lower altitudes.

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3 years ago

One observer stands on a train moving at a constant speed, and one observer stands at rest on the ground. The person on the trai

Anna11 [10]

Answer:

Option D.

Value cannot be calculated without knowing the speed of the train

Explanation:

The speed of the beam can only be calculated accurately when the speed of the train is put into consideration. Based of the theory of relativity, the observer is on the ground, and the train is moving with the beam of light inside it. This causes a variation in the reference frames when making judgements of the speed of the beam. The speed of the beam will be more accurate if the observer is moving at the same sped of the train, or the train is stationary.

To get the correct answer, we have to subtract the speed of the train from the speed calculated.

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3 years ago

A 403.0-kg copper bar is melted in a smelter. The initial temperature of the copper is 320.0 K. How much heat must the smelter p

aleksklad [387]

The answer is 2.49 x 10^5 KJ. This was obtained (1) use the formula for specific heat to achieve Q or heat then (2) get the energy to melt the copper lastly (3) Subtract both work and the total energy required to completely melt the copper bar is achieved.

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4 years ago

Read 2 more answers

Sarah, whose mass is 40 kg, is on her way to school after a winter storm when she accidentally slips on a patch of ice whose coe

RideAnS [48]

Sarah's acceleration is $-0.49 m/s^2$

Explanation:

The force of kinetic friction acting on Sarah has a magnitude which is given by:

$F_f = \mu mg$

where

$\mu$ is the coefficient of kinetic friction

m is Sarah's mass

g is the acceleration of gravity

Moreover, according to Newton's second law of motion, we know that the net force on Sarah is equal to its mass times its acceleration:

$F=ma$

where a is the acceleration

Since the force of friction is the only force acting on Sarah, we can say that the net force is equal to the force of friction, therefore:

$F=-\mu mg = ma$

where the negative sign is due to the fact that the force of friction has a direction opposite to the motion of Sarah. Solving for a, we find

$a=-\mu g$

And substituting the following values:

$\mu = 0.05$ (coefficient of friction)

$g=9.81 m/s^2$ (acceleration of gravity)

we find:

$a=-(0.05)(9.81)=-0.49 m/s^2$

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3 years ago

A child wearing socks is trying to see how far he can slide across his kitchen floor. If

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Answer:

The coefficient of static friction between the ground and the soles of a runner’s shoes is 0.98. What is the maximum speed in which the runner can accelerate without slipping if they have a mass of 73 kg?

Explanation:

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3 years ago