Two cars start from rest at a red stop light. when the light turns green, both cars accelerate forward. the blue car accelerates uniformly at a rate of 4.3 m/s2 for 3.3 seconds. it then continues at a constant speed for 14.3 seconds, before applying the brakes such that the car’s speed decreases uniformly coming to rest 253.26 meters from where it started. the yellow car accelerates uniformly for the entire distance, finally catching the blue car just as the blue car comes to a stop.

1)

how fast is the blue car going 2.6 seconds after it starts?

how fast is the blue car going 7.2 seconds after it starts?

how far does the blue car travel before its brakes are applied to slow down?

what is the acceleration of the blue car once the brakes are applied?

what is the total time the blue car is moving?

what is the acceleration of the yellow car?

negative sign denotes deceleration.

Explanation:

Given:

1)

Speed of blue car after 2.6 seconds of starting the motion:

Applying the equation of motion:

Speed of blue car after 7.2 seconds of starting the motion:

∵The car accelerates uniformly for 3.3 seconds after which its speed becomes uniform for the next 14.3 second before it applies the brake.

so,

Distance travelled by the blue car before application of brakes:

This distance will be (distance travelled during the accelerated motion) + (distance travelled at uniform motion)

Now the distance travelled during the accelerated motion:

Now the distance travelled at uniform motion:

Finally:

Acceleration of the blue car once the brakes are applied

Here we have:

initial velocity,

final velocity,

distance covered while deceleration,

Using the equation of motion:

negative sign denotes deceleration.

The total time for which the blue car moves:

........................(1)

Now the time taken to stop the blue car after application of brakes:

Using the eq. of motion:

Putting respective values in eq. (1)

For the acceleration of the yellow car:

We apply the law of motion:

Here the time taken by the yellow car is same for the same distance as it intercepts just before the stopping of blue car.

Now,

-first use of geothermal energy occurred more than 10,000 years ago in north america by american paleo-indians

-the first industrial use of geothermal energy began near pisa, italy in late 18th century

-in 1904, italian scientist piero ginori conti invented the first geothermal electric power plant in which steam was used to generate the power

-with the above experiment, the first geothermal plant in usa started in 1922 with a capacity of 250 kilowatts

-however, in 1946 first ground-source geothermal heat pump installed at commonwealth building in portland, oregon

-during the 1960’s, pacific gas and electric began operation of first large scale geothermal power plant in san francisco, producing 11 megawatts

-in 1973, when oil crisis began many countries began looking for renewable energy sources and by 1980’s geothermal heat pumps (ghp) started gaining popularity in order to reduce heating and cooling costs

-as effect of climate change started showing results, governments of various countries joined hands to fight against it, for which kyoto protocol was signed in japan in 1997, laid out emission targets for rich countries and required that they transfer funds and technology to developing countries, 184 countries have ratified it

hope this