a model car moves round a circular path of radius 0.3m at 2rev per second. what is the speed of the car and angular speed​

If you're traveling round at 2 revolutions per second then you are travelling with a frequency(f) of 2Hz.

Period (T)= 1/f

So T=1/2=0.5 seconds

You are travelling around a circle radius 0.3m so the circumference is 2πr

2π*0.3=0.6π m

You are travelling 2 times this distance in 1 second and as speed=distance/time

Speed=(2*0.6π)/1

=1.2π m/s

~3.77m/s

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answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.