Physics, 28.12.2019 03:31 zoeyruckel

An elevator whose mass is m = 400 kilograms is supported by a cable. a frictional force of f = 80 newtons is applied to the elevator as it moves. determine the tension t in the cable when the elevator is:

a.) stationary;
b.) moving upward while accelerating at 2.8 m/s2;
c.) moving upward with a constant velocity-magnitude of 5 m/s;
d.) accelerating downward at 2.8 m/s2 with velocity downward;
e.) moving downward with a constant velocity-magnitude of 5 m/s.

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Answer from: larry5007

3924 N

5124 N

4004 N

2884 N

4004 N

Explanation:

m = Mass of elevator = 400 kg

g = Acceleration due to gravity = 9.81 m/s²

a = Acceleration

f = Friction force = 80 N

When the elevator is stationary only the acceleration due to gravity will be acting on it

Tension

$T=mg\\\Rightarrow T=400\times 9.81\\\Rightarrow T=3924\ N$

The tension is 3924 N

The balanced force equation would be

$T-mg-f=ma\\\Rightarrow T=ma+mg+f\\\Rightarrow T=400\times 2.8+400\times 9.81+80\\\Rightarrow T=5124\ N$

The tension is 5124 N

When velocity is constant acceleration is zero

$T-mg-f=0\\\Rightarrow T=mg+f\\\Rightarrow T=400\times 9.81+80\\\Rightarrow T=4004\ N$

The tension is 4004 N

$T-mg-f=-ma\\\Rightarrow T=-ma+mg+f\\\Rightarrow T=-400\times 2.8+400\times 9.81+80\\\Rightarrow T=2884\ N$

The tension would be 2884 N

When velocity is constant acceleration is zero

$T-mg-f=0\\\Rightarrow T=mg+f\\\Rightarrow T=400\times 9.81+80\\\Rightarrow T=4004\ N$

The tension is 4004 N

Answer from: Quest

learn it on the intertant so you can solve

Answer from: Quest

-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

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An elevator whose mass is m = 400 kilograms is supported by a cable. a frictional force of f = 80 ne...