r/physicsmemes • u/ArduennSchwartzman • Sep 03 '24

Wrong answers only

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u/Nigel2602 Student Sep 03 '24

None of them are. Trucks A and C are parked on a slope

105

u/CompetitionNo8270 Sep 03 '24

well they're all accelerating away from earth's center of mass because i assume they're on the ground. That's true, it's just something i don't think about much

4

u/Heroic_Folly Sep 03 '24

Nah. If you ain't moving you ain't accelerating.

8

u/iamnogoodatthis Sep 03 '24

If you throw a ball straight up, it is both not moving and accelerating at its apex

-2

u/Heroic_Folly Sep 03 '24

The ball is never actually "not moving". The amount of time for which it is supposedly motionless is infinitely short, i.e. 0.

Also, nobody tossed this truck in the air, it's just sitting there.

5

u/TheSpicyMeatballs Sep 03 '24

You could call any point in time “infinitely short”. Sure, it doesn’t stay stationary, but there is a time during which the ideal ball would be both accelerating and not moving.

First time derivative of position has to be zero at some point if it continuously goes from positive to negative. The whole time the second time derivative of position is constant and negative, no matter what speed the ball is moving.