A roller coaster begins at rest 120 m above the ground, as shown. Assume no friction from the wheels and air, and that no
energy is lost to heat, sound, and so on. The radius of the loop
is 40 m. Find the speed of the roller coaster at points E and F.
Note:- Use
10 m/s2.
9=

the correct choice is a .

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he made 11 calls in one day

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

answer///terminator or twilight zone;